diff --git a/code/__DEFINES/mod.dm b/code/__DEFINES/mod.dm
index dcfcf028d08..1a4bed1ca99 100644
--- a/code/__DEFINES/mod.dm
+++ b/code/__DEFINES/mod.dm
@@ -57,9 +57,5 @@
 
 /// Global list of all /datum/mod_theme
 GLOBAL_LIST_INIT(mod_themes, setup_mod_themes())
-/// Global cache of mod skins to masks per different configuration of pulled out parts.
-GLOBAL_LIST_EMPTY(mod_masks)
-/// Global cache of mod skins to deployed parts to module icon states
-GLOBAL_LIST_EMPTY(mod_module_overlays)
 /// Global list of all ids associated to a /datum/mod_link instance
 GLOBAL_LIST_EMPTY(mod_link_ids)
diff --git a/code/game/objects/structures/mannequin.dm b/code/game/objects/structures/mannequin.dm
index e4cbfc7d629..2260751bbf7 100644
--- a/code/game/objects/structures/mannequin.dm
+++ b/code/game/objects/structures/mannequin.dm
@@ -114,49 +114,12 @@
 		var/obj/item/worn_item = worn_items[slot_flag]
 		if(!worn_item)
 			continue
-		var/default_layer = 0
-		var/default_icon = null
+		var/default_icon = get_default_icon_by_slot(text2num(slot_flag))
+		var/default_layer = get_default_layer_by_slot(text2num(slot_flag))
 		var/female_icon = NO_FEMALE_UNIFORM
-		switch(text2num(slot_flag)) //this kinda sucks because build worn icon kinda sucks
-			if(ITEM_SLOT_HEAD)
-				default_layer = HEAD_LAYER
-				default_icon = 'icons/mob/clothing/head/default.dmi'
-			if(ITEM_SLOT_EYES)
-				default_layer = GLASSES_LAYER
-				default_icon = 'icons/mob/clothing/eyes.dmi'
-			if(ITEM_SLOT_EARS)
-				default_layer = EARS_LAYER
-				default_icon = 'icons/mob/clothing/ears.dmi'
-			if(ITEM_SLOT_MASK)
-				default_layer = FACEMASK_LAYER
-				default_icon = 'icons/mob/clothing/mask.dmi'
-			if(ITEM_SLOT_NECK)
-				default_layer = NECK_LAYER
-				default_icon = 'icons/mob/clothing/neck.dmi'
-			if(ITEM_SLOT_BACK)
-				default_layer = BACK_LAYER
-				default_icon = 'icons/mob/clothing/back.dmi'
-			if(ITEM_SLOT_BELT)
-				default_layer = BELT_LAYER
-				default_icon = 'icons/mob/clothing/belt.dmi'
-			if(ITEM_SLOT_ID)
-				default_layer = ID_LAYER
-				default_icon = 'icons/mob/clothing/id.dmi'
-			if(ITEM_SLOT_ICLOTHING)
-				default_layer = UNIFORM_LAYER
-				default_icon = DEFAULT_UNIFORM_FILE
-				if(body_type == FEMALE && istype(worn_item, /obj/item/clothing/under))
-					var/obj/item/clothing/under/worn_jumpsuit = worn_item
-					female_icon = worn_jumpsuit.female_sprite_flags
-			if(ITEM_SLOT_OCLOTHING)
-				default_layer = SUIT_LAYER
-				default_icon = DEFAULT_SUIT_FILE
-			if(ITEM_SLOT_GLOVES)
-				default_layer = GLOVES_LAYER
-				default_icon = 'icons/mob/clothing/hands.dmi'
-			if(ITEM_SLOT_FEET)
-				default_layer = SHOES_LAYER
-				default_icon = DEFAULT_SHOES_FILE
+		if(body_type == FEMALE && istype(worn_item, /obj/item/clothing/under))
+			var/obj/item/clothing/under/worn_jumpsuit = worn_item
+			female_icon = worn_jumpsuit.female_sprite_flags
 		. += worn_item.build_worn_icon(default_layer, default_icon, female_uniform = female_icon)
 
 /obj/structure/mannequin/attack_hand_secondary(mob/user, list/modifiers)
diff --git a/code/modules/antagonists/clown_ops/clownop.dm b/code/modules/antagonists/clown_ops/clownop.dm
index 2fd2daa7489..9e2b79102b1 100644
--- a/code/modules/antagonists/clown_ops/clownop.dm
+++ b/code/modules/antagonists/clown_ops/clownop.dm
@@ -78,8 +78,7 @@
 
 /datum/outfit/clown_operative/post_equip(mob/living/carbon/human/H, visuals_only)
 	var/obj/item/mod/module/armor_booster/booster = locate() in H.back
-	booster.active = TRUE
-	H.update_worn_back()
+	booster.activate()
 
 /datum/outfit/clown_operative_elite
 	name = "Clown Operative (Elite, Preview only)"
@@ -89,5 +88,4 @@
 
 /datum/outfit/clown_operative_elite/post_equip(mob/living/carbon/human/H, visuals_only)
 	var/obj/item/mod/module/armor_booster/booster = locate() in H.back
-	booster.active = TRUE
-	H.update_worn_back()
+	booster.activate()
diff --git a/code/modules/antagonists/nukeop/outfits.dm b/code/modules/antagonists/nukeop/outfits.dm
index 32fe7dfd5c0..9ecfbb9f991 100644
--- a/code/modules/antagonists/nukeop/outfits.dm
+++ b/code/modules/antagonists/nukeop/outfits.dm
@@ -188,8 +188,7 @@
 
 /datum/outfit/nuclear_operative/post_equip(mob/living/carbon/human/H, visuals_only)
 	var/obj/item/mod/module/armor_booster/booster = locate() in H.back
-	booster.active = TRUE
-	H.update_worn_back()
+	booster.activate()
 
 /datum/outfit/nuclear_operative_elite
 	name = "Nuclear Operative (Elite, Preview only)"
@@ -201,8 +200,7 @@
 
 /datum/outfit/nuclear_operative_elite/post_equip(mob/living/carbon/human/H, visuals_only)
 	var/obj/item/mod/module/armor_booster/booster = locate() in H.back
-	booster.active = TRUE
-	H.update_worn_back()
+	booster.activate()
 	var/obj/item/shield/energy/shield = locate() in H.held_items
 	shield.icon_state = "[shield.base_icon_state]1"
 	H.update_held_items()
diff --git a/code/modules/mob/living/carbon/carbon_update_icons.dm b/code/modules/mob/living/carbon/carbon_update_icons.dm
index 6a216fda617..abc96cb33d3 100644
--- a/code/modules/mob/living/carbon/carbon_update_icons.dm
+++ b/code/modules/mob/living/carbon/carbon_update_icons.dm
@@ -638,3 +638,57 @@ GLOBAL_LIST_EMPTY(masked_leg_icons_cache)
 	new_leg_appearance_lower.layer = -BODYPARTS_LOW_LAYER
 	. += new_leg_appearance_lower
 	return .
+
+/proc/get_default_icon_by_slot(slot_flag)
+	switch(slot_flag)
+		if(ITEM_SLOT_HEAD)
+			return 'icons/mob/clothing/head/default.dmi'
+		if(ITEM_SLOT_EYES)
+			return 'icons/mob/clothing/eyes.dmi'
+		if(ITEM_SLOT_EARS)
+			return 'icons/mob/clothing/ears.dmi'
+		if(ITEM_SLOT_MASK)
+			return 'icons/mob/clothing/mask.dmi'
+		if(ITEM_SLOT_NECK)
+			return 'icons/mob/clothing/neck.dmi'
+		if(ITEM_SLOT_BACK)
+			return 'icons/mob/clothing/back.dmi'
+		if(ITEM_SLOT_BELT)
+			return 'icons/mob/clothing/belt.dmi'
+		if(ITEM_SLOT_ID)
+			return 'icons/mob/clothing/id.dmi'
+		if(ITEM_SLOT_ICLOTHING)
+			return DEFAULT_UNIFORM_FILE
+		if(ITEM_SLOT_OCLOTHING)
+			return DEFAULT_SUIT_FILE
+		if(ITEM_SLOT_GLOVES)
+			return 'icons/mob/clothing/hands.dmi'
+		if(ITEM_SLOT_FEET)
+			return DEFAULT_SHOES_FILE
+
+/proc/get_default_layer_by_slot(slot_flag)
+	switch(text2num(slot_flag))
+		if(ITEM_SLOT_HEAD)
+			return HEAD_LAYER
+		if(ITEM_SLOT_EYES)
+			return GLASSES_LAYER
+		if(ITEM_SLOT_EARS)
+			return EARS_LAYER
+		if(ITEM_SLOT_MASK)
+			return FACEMASK_LAYER
+		if(ITEM_SLOT_NECK)
+			return NECK_LAYER
+		if(ITEM_SLOT_BACK)
+			return BACK_LAYER
+		if(ITEM_SLOT_BELT)
+			return BELT_LAYER
+		if(ITEM_SLOT_ID)
+			return ID_LAYER
+		if(ITEM_SLOT_ICLOTHING)
+			return UNIFORM_LAYER
+		if(ITEM_SLOT_OCLOTHING)
+			return SUIT_LAYER
+		if(ITEM_SLOT_GLOVES)
+			return GLOVES_LAYER
+		if(ITEM_SLOT_FEET)
+			return SHOES_LAYER
diff --git a/code/modules/mod/mod_activation.dm b/code/modules/mod/mod_activation.dm
index a31d7b43742..12de6ac26d7 100644
--- a/code/modules/mod/mod_activation.dm
+++ b/code/modules/mod/mod_activation.dm
@@ -93,7 +93,7 @@
 				RegisterSignal(part, COMSIG_ATOM_EXITED, PROC_REF(on_overslot_exit))
 	if(wearer.equip_to_slot_if_possible(part, part.slot_flags, qdel_on_fail = FALSE, disable_warning = TRUE))
 		ADD_TRAIT(part, TRAIT_NODROP, MOD_TRAIT)
-		wearer.update_clothing(slot_flags)
+		wearer.update_clothing(slot_flags|part.slot_flags)
 		SEND_SIGNAL(src, COMSIG_MOD_PART_DEPLOYED, user, part_datum)
 		if(user)
 			wearer.visible_message(span_notice("[wearer]'s [part.name] deploy[part.p_s()] with a mechanical hiss."),
@@ -131,7 +131,9 @@
 		return FALSE
 	if(SEND_SIGNAL(src, COMSIG_MOD_PART_RETRACTING, user, part_datum) & MOD_CANCEL_RETRACTION)
 		return FALSE
+	var/unsealing = FALSE
 	if(active && part_datum.sealed)
+		unsealing = TRUE
 		if(instant)
 			seal_part(part, is_sealed = FALSE)
 		else if(!delayed_seal_part(part))
@@ -144,13 +146,14 @@
 		var/obj/item/overslot = part_datum.overslotting
 		if(!QDELING(wearer) && !wearer.equip_to_slot_if_possible(overslot, overslot.slot_flags, qdel_on_fail = FALSE, disable_warning = TRUE))
 			wearer.dropItemToGround(overslot, force = TRUE, silent = TRUE)
-	wearer.update_clothing(slot_flags)
+	wearer.update_clothing(slot_flags|part.slot_flags)
 	if(!user)
 		return TRUE
 	wearer.visible_message(span_notice("[wearer]'s [part.name] retract[part.p_s()] back into [src] with a mechanical hiss."),
 		span_notice("[part] retract[part.p_s()] back into [src] with a mechanical hiss."),
 		span_hear("You hear a mechanical hiss."))
-	playsound(src, 'sound/vehicles/mecha/mechmove03.ogg', 25, TRUE, SHORT_RANGE_SOUND_EXTRARANGE)
+	if (!unsealing)
+		playsound(src, 'sound/vehicles/mecha/mechmove03.ogg', 25, TRUE, SHORT_RANGE_SOUND_EXTRARANGE)
 	return TRUE
 
 /// Starts the activation sequence, where parts of the suit activate one by one until the whole suit is on.
@@ -268,7 +271,6 @@
 		part.heat_protection = NONE
 		part.cold_protection = NONE
 		part.alternate_worn_layer = part_datum.unsealed_layer
-	generate_suit_mask()
 	update_speed()
 	wearer.update_clothing(part.slot_flags | slot_flags)
 	wearer.update_obscured_slots(part.visor_flags_inv)
@@ -281,7 +283,7 @@
 		for(var/obj/item/mod/module/module as anything in modules)
 			if(module.part_activated || !module.has_required_parts(mod_parts, need_active = TRUE))
 				continue
-			module.on_part_activation()
+				module.on_part_activation()
 			module.part_activated = TRUE
 	else
 		for(var/obj/item/mod/module/module as anything in modules)
@@ -300,23 +302,16 @@
 	active = is_on
 	if(active)
 		for(var/obj/item/mod/module/module as anything in modules)
-			if(module.part_activated || !module.has_required_parts(mod_parts, need_active = TRUE))
-				continue
-			module.on_part_activation()
-			module.part_activated = TRUE
+			if(!module.part_activated && module.has_required_parts(mod_parts, need_active = TRUE))
+				module.on_part_activation()
 	else
 		for(var/obj/item/mod/module/module as anything in modules)
 			if(!module.part_activated)
 				continue
 			module.on_part_deactivation()
-			module.part_activated = FALSE
-			if(!module.active || (module.allow_flags & MODULE_ALLOW_INACTIVE))
-				continue
-			module.deactivate(display_message = FALSE)
 	update_charge_alert()
 	update_appearance(UPDATE_ICON_STATE)
-	generate_suit_mask()
-	wearer.update_clothing(slot_flags)
+	wearer.update_clothing()
 
 /// Quickly deploys all the suit parts and if successful, seals them and turns on the suit. Intended mostly for outfits.
 /obj/item/mod/control/proc/quick_activation()
diff --git a/code/modules/mod/mod_control.dm b/code/modules/mod/mod_control.dm
index f64539bbbd5..bf6966499fa 100644
--- a/code/modules/mod/mod_control.dm
+++ b/code/modules/mod/mod_control.dm
@@ -114,13 +114,10 @@
 	if(core)
 		QDEL_NULL(core)
 	QDEL_NULL(mod_link)
-	for(var/datum/mod_part/part_datum as anything in get_part_datums(all = TRUE))
-		var/obj/item/part_item = part_datum.part_item
-		part_datum.part_item = null
-		part_datum.overslotting = null
-		mod_parts -= part_datum
-		if(!QDELING(part_item))
-			qdel(part_item)
+	for(var/part_key in mod_parts)
+		var/datum/mod_part/part_datum = mod_parts[part_key]
+		mod_parts -= part_key
+		qdel(part_datum)
 	return ..()
 
 /obj/item/mod/control/atom_destruction(damage_flag)
@@ -443,11 +440,14 @@
 	CRASH("get_part_datum called with incorrect item [part] passed.")
 
 /obj/item/mod/control/proc/get_part_from_slot(slot)
-	var/datum/mod_part/part = mod_parts["[slot]"]
-	return part?.part_item
+	RETURN_TYPE(/obj/item)
+	return get_part_datum_from_slot(slot)?.part_item
 
 /obj/item/mod/control/proc/get_part_datum_from_slot(slot)
-	return mod_parts["[slot]"]
+	RETURN_TYPE(/datum/mod_part)
+	for (var/part_key in mod_parts)
+		if (text2num(part_key) & slot)
+			return mod_parts[part_key]
 
 /obj/item/mod/control/proc/set_wearer(mob/living/carbon/human/user)
 	if(wearer == user)
@@ -481,21 +481,6 @@
 		covered_slots |= part.slot_flags
 	return covered_slots
 
-/obj/item/mod/control/proc/generate_suit_mask()
-	var/list/parts = get_parts(all = TRUE)
-	var/covered_slots = get_sealed_slots(parts)
-	if(GLOB.mod_masks[skin])
-		if(GLOB.mod_masks[skin]["[covered_slots]"])
-			return GLOB.mod_masks[skin]["[covered_slots]"]
-	else
-		GLOB.mod_masks[skin] = list()
-	var/icon/slot_mask = icon('icons/blanks/32x32.dmi', "nothing")
-	for(var/obj/item/part as anything in parts)
-		slot_mask.Blend(icon(part.worn_icon, part.icon_state), ICON_OVERLAY)
-	slot_mask.Blend("#fff", ICON_ADD)
-	GLOB.mod_masks[skin]["[covered_slots]"] = slot_mask
-	return GLOB.mod_masks[skin]["[covered_slots]"]
-
 /obj/item/mod/control/proc/clean_up()
 	if(QDELING(src))
 		unset_wearer()
@@ -602,7 +587,6 @@
 	modules += new_module
 	complexity += new_module.complexity
 	new_module.mod = src
-	new_module.RegisterSignal(src, COMSIG_ITEM_GET_WORN_OVERLAYS, TYPE_PROC_REF(/obj/item/mod/module, add_module_overlay))
 	new_module.on_install()
 	if(wearer)
 		new_module.on_equip()
@@ -622,7 +606,6 @@
 		old_module.on_part_deactivation(deleting = deleting)
 		if(old_module.active)
 			old_module.deactivate(display_message = !deleting, deleting = deleting)
-	old_module.UnregisterSignal(src, COMSIG_ITEM_GET_WORN_OVERLAYS)
 	old_module.on_uninstall(deleting = deleting)
 	QDEL_LIST_ASSOC_VAL(old_module.pinned_to)
 	old_module.mod = null
diff --git a/code/modules/mod/mod_part.dm b/code/modules/mod/mod_part.dm
index 88f8024628d..a184df7f7a0 100644
--- a/code/modules/mod/mod_part.dm
+++ b/code/modules/mod/mod_part.dm
@@ -18,5 +18,29 @@
 	var/obj/item/overslotting = null
 
 /datum/mod_part/Destroy()
+	// To avoid qdel loops in MOD control units, since they're also a part
+	if (!QDELING(part_item))
+		qdel(part_item)
 	part_item = null
+	overslotting = null
 	return ..()
+
+/datum/mod_part/proc/set_item(obj/item/new_part)
+	part_item = new_part
+	RegisterSignal(part_item, COMSIG_ITEM_GET_SEPARATE_WORN_OVERLAYS, PROC_REF(get_separate_worn_overlays))
+
+// If we're overslotting an item, add its visual as an underlay
+/datum/mod_part/proc/get_separate_worn_overlays(obj/item/source, list/overlays, mutable_appearance/standing, mutable_appearance/draw_target, isinhands, icon_file)
+	SIGNAL_HANDLER
+
+	if (!overslotting || sealed)
+		return
+
+	var/checked_slot = source.slot_flags
+	if (ismob(source.loc))
+		var/mob/as_mob = source.loc
+		checked_slot = as_mob.get_slot_by_item(source)
+	var/mutable_appearance/worn_overlay = overslotting.build_worn_icon(default_layer = -draw_target.layer + 0.1, default_icon_file = get_default_icon_by_slot(checked_slot))
+	for (var/mutable_appearance/overlay in worn_overlay.overlays)
+		overlay.layer = draw_target.layer + 0.1
+	overlays += worn_overlay
diff --git a/code/modules/mod/mod_theme.dm b/code/modules/mod/mod_theme.dm
index 7ac3aeda0cc..1f9de066352 100644
--- a/code/modules/mod/mod_theme.dm
+++ b/code/modules/mod/mod_theme.dm
@@ -106,7 +106,7 @@
 	mod.ui_theme = ui_theme
 	mod.charge_drain = charge_drain
 	var/datum/mod_part/control_part_datum = new()
-	control_part_datum.part_item = mod
+	control_part_datum.set_item(mod)
 	mod.mod_parts["[mod.slot_flags]"] = control_part_datum
 	for(var/path in variants[default_skin])
 		if(!ispath(path))
@@ -116,7 +116,7 @@
 			var/obj/item/clothing/chestplate = mod_part
 			chestplate.allowed |= allowed_suit_storage
 		var/datum/mod_part/part_datum = new()
-		part_datum.part_item = mod_part
+		part_datum.set_item(mod_part)
 		mod.mod_parts["[mod_part.slot_flags]"] = part_datum
 		parts += mod_part
 
diff --git a/code/modules/mod/modules/_module.dm b/code/modules/mod/modules/_module.dm
index 2fec22edbc6..fe3f02fc99b 100644
--- a/code/modules/mod/modules/_module.dm
+++ b/code/modules/mod/modules/_module.dm
@@ -172,9 +172,9 @@
 			update_signal(used_button)
 			balloon_alert(mod.wearer, "[src] activated, [used_button]-click to use")
 	active = TRUE
-	mod.wearer.update_clothing(mod.slot_flags)
 	SEND_SIGNAL(src, COMSIG_MODULE_ACTIVATED)
 	on_activation()
+	update_clothing_slots()
 	return TRUE
 
 /// Called when the module is deactivated
@@ -191,11 +191,22 @@
 		else
 			UnregisterSignal(mod.wearer, used_signal)
 			used_signal = null
-	mod.wearer.update_clothing(mod.slot_flags)
 	SEND_SIGNAL(src, COMSIG_MODULE_DEACTIVATED, mod.wearer)
 	on_deactivation(display_message = TRUE, deleting = FALSE)
+	update_clothing_slots()
 	return TRUE
 
+/// Call to update all slots visually affected by this module
+/obj/item/mod/module/proc/update_clothing_slots()
+	var/updated_slots = mod.slot_flags
+	if (mask_worn_overlay)
+		for (var/obj/item/part as anything in mod.get_parts())
+			updated_slots |= part.slot_flags
+	else if (length(required_slots))
+		for (var/slot in required_slots)
+			updated_slots |= slot
+	mod.wearer.update_clothing(updated_slots)
+
 /// Called when the module is used
 /obj/item/mod/module/proc/used()
 	if(!COOLDOWN_FINISHED(src, cooldown_timer))
@@ -212,7 +223,7 @@
 		return FALSE
 	start_cooldown()
 	addtimer(CALLBACK(mod.wearer, TYPE_PROC_REF(/mob, update_clothing), mod.slot_flags), cooldown_time+1) //need to run it a bit after the cooldown starts to avoid conflicts
-	mod.wearer.update_clothing(mod.slot_flags)
+	update_clothing_slots()
 	SEND_SIGNAL(src, COMSIG_MODULE_USED)
 	on_use()
 	return TRUE
@@ -263,11 +274,38 @@
 
 /// Called from MODsuit's install() proc, so when the module is installed
 /obj/item/mod/module/proc/on_install()
-	return
+	SHOULD_CALL_PARENT(TRUE)
+
+	if (mask_worn_overlay)
+		for (var/obj/item/part as anything in mod.get_parts(all = TRUE))
+			RegisterSignal(part, COMSIG_ITEM_GET_SEPARATE_WORN_OVERLAYS, PROC_REF(add_module_overlay))
+		return
+
+	if (!length(required_slots))
+		RegisterSignal(mod, COMSIG_ITEM_GET_SEPARATE_WORN_OVERLAYS, PROC_REF(add_module_overlay))
+		return
+
+	var/obj/item/part = mod.get_part_from_slot(required_slots[1])
+	RegisterSignal(part, COMSIG_ITEM_GET_SEPARATE_WORN_OVERLAYS, PROC_REF(add_module_overlay))
 
 /// Called from MODsuit's uninstall() proc, so when the module is uninstalled
 /obj/item/mod/module/proc/on_uninstall(deleting = FALSE)
-	return
+	SHOULD_CALL_PARENT(TRUE)
+
+	if (deleting)
+		return
+
+	if (mask_worn_overlay)
+		for (var/obj/item/part as anything in mod.get_parts(all = TRUE))
+			UnregisterSignal(part, COMSIG_ITEM_GET_SEPARATE_WORN_OVERLAYS)
+		return
+
+	if (!length(required_slots))
+		UnregisterSignal(mod, COMSIG_ITEM_GET_SEPARATE_WORN_OVERLAYS)
+		return
+
+	var/obj/item/part = mod.get_part_from_slot(required_slots[1])
+	UnregisterSignal(part, COMSIG_ITEM_GET_SEPARATE_WORN_OVERLAYS)
 
 /// Called when the MODsuit is activated
 /obj/item/mod/module/proc/on_part_activation()
@@ -335,26 +373,44 @@
 		qdel(src)
 
 /// Adds the worn overlays to the suit.
-/obj/item/mod/module/proc/add_module_overlay(obj/item/source, list/overlays, mutable_appearance/standing, isinhands, icon_file)
+/obj/item/mod/module/proc/add_module_overlay(obj/item/source, list/overlays, mutable_appearance/standing, mutable_appearance/draw_target, isinhands, icon_file)
 	SIGNAL_HANDLER
 
-	overlays += generate_worn_overlay(standing)
+	if (isinhands)
+		return
+
+	var/list/added_overlays = generate_worn_overlay(source, standing)
+	if (!added_overlays)
+		return
+
+	if (!mask_worn_overlay)
+		overlays += added_overlays
+		return
+
+	for (var/mutable_appearance/overlay as anything in added_overlays)
+		overlay.add_filter("mod_mask_overlay", 1, alpha_mask_filter(icon = icon(draw_target.icon, draw_target.icon_state)))
+		overlays += overlay
 
 /// Generates an icon to be used for the suit's worn overlays
-/obj/item/mod/module/proc/generate_worn_overlay(mutable_appearance/standing)
+/obj/item/mod/module/proc/generate_worn_overlay(obj/item/source, mutable_appearance/standing)
+	if(!mask_worn_overlay)
+		if(!has_required_parts(mod.mod_parts, need_active = TRUE))
+			return
+	else
+		var/datum/mod_part/part_datum = mod.get_part_datum(source)
+		if (!part_datum?.sealed)
+			return
+
 	. = list()
-	if(!mod.active || !has_required_parts(mod.mod_parts, need_active = TRUE))
-		return
 	var/used_overlay = get_current_overlay_state()
 	if (!used_overlay)
 		return
-	var/mutable_appearance/module_icon
-	if(mask_worn_overlay)
-		module_icon = mutable_appearance(get_module_icon_cache(used_overlay), layer = standing.layer + 0.1)
-	else
-		module_icon = mutable_appearance(overlay_icon_file, used_overlay, layer = standing.layer + 0.1)
-	if(!use_mod_colors)
-		module_icon.appearance_flags |= RESET_COLOR
+
+	var/mutable_appearance/module_icon = mutable_appearance(overlay_icon_file, used_overlay, layer = standing.layer + 0.1)
+	if(use_mod_colors)
+		module_icon.color = mod.color
+		if (mod.cached_color_filter)
+			module_icon = filter_appearance_recursive(module_icon, mod.cached_color_filter)
 
 	. += module_icon
 	SEND_SIGNAL(src, COMSIG_MODULE_GENERATE_WORN_OVERLAY, ., standing)
@@ -368,22 +424,6 @@
 		return overlay_state_inactive
 	return null
 
-/obj/item/mod/module/proc/get_module_icon_cache(used_overlay)
-	var/covered_slots = mod.get_sealed_slots(mod.get_parts(all = TRUE))
-	if (GLOB.mod_module_overlays[mod.skin])
-		if (GLOB.mod_module_overlays[mod.skin]["[covered_slots]"])
-			if (GLOB.mod_module_overlays[mod.skin]["[covered_slots]"][used_overlay])
-				return GLOB.mod_module_overlays[mod.skin]["[covered_slots]"][used_overlay]
-		else
-			GLOB.mod_module_overlays[mod.skin]["[covered_slots]"] = list()
-	else
-		GLOB.mod_module_overlays[mod.skin] = list()
-		GLOB.mod_module_overlays[mod.skin]["[covered_slots]"] = list()
-	var/icon/mod_mask = icon(mod.generate_suit_mask())
-	mod_mask.Blend(icon(overlay_icon_file, used_overlay), ICON_MULTIPLY)
-	GLOB.mod_module_overlays[mod.skin]["[covered_slots]"][used_overlay] = mod_mask
-	return GLOB.mod_module_overlays[mod.skin]["[covered_slots]"][used_overlay]
-
 /// Updates the signal used by active modules to be activated
 /obj/item/mod/module/proc/update_signal(value)
 	switch(value)
diff --git a/code/modules/mod/modules/modules_antag.dm b/code/modules/mod/modules/modules_antag.dm
index 9dce0940b3f..7f9d113b124 100644
--- a/code/modules/mod/modules/modules_antag.dm
+++ b/code/modules/mod/modules/modules_antag.dm
@@ -90,7 +90,7 @@
 	if (!active)
 		module_slowdowns += space_slowdown
 
-/obj/item/mod/module/armor_booster/generate_worn_overlay(mutable_appearance/standing)
+/obj/item/mod/module/armor_booster/generate_worn_overlay(obj/item/source, mutable_appearance/standing)
 	overlay_state_inactive = "[initial(overlay_state_inactive)]-[mod.skin]"
 	overlay_state_active = "[initial(overlay_state_active)]-[mod.skin]"
 	return ..()
@@ -105,9 +105,11 @@
 		REMOVE_TRAIT(mod.wearer, TRAIT_HEAD_INJURY_BLOCKED, REF(src))
 
 /obj/item/mod/module/armor_booster/on_install()
+	. = ..()
 	RegisterSignal(mod, COMSIG_MOD_GET_VISOR_OVERLAY, PROC_REF(on_visor_overlay))
 
-/obj/item/mod/module/armor_booster/on_uninstall(deleting)
+/obj/item/mod/module/armor_booster/on_uninstall(deleting = FALSE)
+	. = ..()
 	UnregisterSignal(mod, COMSIG_MOD_GET_VISOR_OVERLAY)
 
 /obj/item/mod/module/armor_booster/proc/on_visor_overlay(datum/source,  mutable_appearance/standing, list/overrides)
@@ -241,7 +243,7 @@
 	overlay_state_inactive = "module_insignia"
 	mask_worn_overlay = TRUE
 
-/obj/item/mod/module/insignia/generate_worn_overlay(mutable_appearance/standing)
+/obj/item/mod/module/insignia/generate_worn_overlay(obj/item/source, mutable_appearance/standing)
 	overlay_state_inactive = "[initial(overlay_state_inactive)]-[mod.skin]"
 	. = ..()
 	for(var/mutable_appearance/appearance as anything in .)
@@ -409,6 +411,7 @@
 	var/obj/item/current_disguise
 
 /obj/item/mod/module/chameleon/on_install()
+	. = ..()
 	var/list/all_disguises = sort_list(subtypesof(get_path_by_slot(mod.slot_flags)), GLOBAL_PROC_REF(cmp_typepaths_asc))
 	for(var/clothing_path in all_disguises)
 		var/obj/item/clothing = clothing_path
@@ -418,6 +421,7 @@
 		possible_disguises[chameleon_item_name] = clothing_path
 
 /obj/item/mod/module/chameleon/on_uninstall(deleting = FALSE)
+	. = ..()
 	if(current_disguise)
 		return_look()
 	possible_disguises = null
@@ -449,7 +453,7 @@
 	mod.righthand_file = initial(current_disguise.righthand_file)
 	mod.worn_icon_state = initial(current_disguise.worn_icon_state)
 	mod.inhand_icon_state = initial(current_disguise.inhand_icon_state)
-	mod.wearer.update_clothing(mod.slot_flags)
+	update_clothing_slots()
 	RegisterSignal(mod, COMSIG_MOD_ACTIVATE, PROC_REF(return_look))
 
 /obj/item/mod/module/chameleon/proc/return_look()
@@ -463,7 +467,7 @@
 	mod.righthand_file = initial(mod.righthand_file)
 	mod.worn_icon_state = null
 	mod.inhand_icon_state = null
-	mod.wearer.update_clothing(mod.slot_flags)
+	update_clothing_slots()
 	current_disguise = null
 	UnregisterSignal(mod, COMSIG_MOD_ACTIVATE)
 
@@ -481,10 +485,12 @@
 	var/old_size
 
 /obj/item/mod/module/plate_compression/on_install()
+	. = ..()
 	old_size = mod.w_class
 	mod.update_weight_class(new_size)
 
 /obj/item/mod/module/plate_compression/on_uninstall(deleting = FALSE)
+	. = ..()
 	mod.update_weight_class(old_size)
 	old_size = null
 	if(!mod.loc)
@@ -528,9 +534,11 @@
 	var/list/traits_to_add = list(TRAIT_SILENT_FOOTSTEPS, TRAIT_UNKNOWN, TRAIT_HEAD_INJURY_BLOCKED)
 
 /obj/item/mod/module/infiltrator/on_install()
+	. = ..()
 	ADD_TRAIT(mod, TRAIT_EXAMINE_SKIP, REF(src))
 
 /obj/item/mod/module/infiltrator/on_uninstall(deleting = FALSE)
+	. = ..()
 	REMOVE_TRAIT(mod, TRAIT_EXAMINE_SKIP, REF(src))
 
 /obj/item/mod/module/infiltrator/on_part_activation()
diff --git a/code/modules/mod/modules/modules_engineering.dm b/code/modules/mod/modules/modules_engineering.dm
index 9af2ea0bc5a..018d6d35275 100644
--- a/code/modules/mod/modules/modules_engineering.dm
+++ b/code/modules/mod/modules/modules_engineering.dm
@@ -62,9 +62,11 @@
 	var/list/active_traits = list(TRAIT_NO_SLIP_WATER, TRAIT_NO_SLIP_ICE, TRAIT_NO_SLIP_SLIDE, TRAIT_NEGATES_GRAVITY)
 
 /obj/item/mod/module/magboot/on_install()
+	. = ..()
 	RegisterSignal(mod, COMSIG_MOD_UPDATE_SPEED, PROC_REF(on_update_speed))
 
-/obj/item/mod/module/magboot/on_uninstall(deleting)
+/obj/item/mod/module/magboot/on_uninstall(deleting = FALSE)
+	. = ..()
 	UnregisterSignal(mod, COMSIG_MOD_UPDATE_SPEED)
 
 /obj/item/mod/module/magboot/on_activation()
diff --git a/code/modules/mod/modules/modules_general.dm b/code/modules/mod/modules/modules_general.dm
index 2ddb7ccdc66..3a7c0792b31 100644
--- a/code/modules/mod/modules/modules_general.dm
+++ b/code/modules/mod/modules/modules_general.dm
@@ -25,6 +25,7 @@
 	atom_storage.set_locked(STORAGE_FULLY_LOCKED)
 
 /obj/item/mod/module/storage/on_install()
+	. = ..()
 	var/datum/storage/modstorage = mod.create_storage(max_specific_storage = max_w_class, max_total_storage = max_combined_w_class, max_slots = max_items)
 	modstorage.set_real_location(src)
 	modstorage.allow_big_nesting = big_nesting
@@ -34,6 +35,7 @@
 		RegisterSignal(suit, COMSIG_ITEM_PRE_UNEQUIP, PROC_REF(on_suit_unequip))
 
 /obj/item/mod/module/storage/on_uninstall(deleting = FALSE)
+	. = ..()
 	atom_storage.set_locked(STORAGE_FULLY_LOCKED)
 	QDEL_NULL(mod.atom_storage)
 	if(!deleting)
@@ -328,6 +330,7 @@
 	var/former_visor_mask_flags = NONE
 
 /obj/item/mod/module/mouthhole/on_install()
+	. = ..()
 	var/obj/item/clothing/helmet = mod.get_part_from_slot(ITEM_SLOT_HEAD)
 	if(istype(helmet))
 		former_helmet_flags = helmet.flags_cover
@@ -351,6 +354,7 @@
 	return FALSE
 
 /obj/item/mod/module/mouthhole/on_uninstall(deleting = FALSE)
+	. = ..()
 	if(deleting)
 		return
 	var/obj/item/clothing/helmet = mod.get_part_from_slot(ITEM_SLOT_HEAD)
@@ -375,9 +379,11 @@
 	required_slots = list(ITEM_SLOT_BACK|ITEM_SLOT_BELT)
 
 /obj/item/mod/module/emp_shield/on_install()
+	. = ..()
 	mod.AddElement(/datum/element/empprotection, EMP_PROTECT_ALL)
 
 /obj/item/mod/module/emp_shield/on_uninstall(deleting = FALSE)
+	. = ..()
 	mod.RemoveElement(/datum/element/empprotection, EMP_PROTECT_ALL)
 
 /obj/item/mod/module/emp_shield/advanced
@@ -437,7 +443,7 @@
 	active_power_cost = base_power * light_range
 	return ..()
 
-/obj/item/mod/module/flashlight/generate_worn_overlay(mutable_appearance/standing)
+/obj/item/mod/module/flashlight/generate_worn_overlay(obj/item/source, mutable_appearance/standing)
 	. = ..()
 	if(!active)
 		return
@@ -460,7 +466,7 @@
 				balloon_alert(mod.wearer, "too dark!")
 				return
 			set_light_color(value)
-			mod.wearer.update_clothing(mod.slot_flags)
+			update_clothing_slots()
 		if("light_range")
 			set_light_range(clamp(value, min_range, max_range))
 
@@ -594,12 +600,14 @@
 	var/dna = null
 
 /obj/item/mod/module/dna_lock/on_install()
+	. = ..()
 	RegisterSignal(mod, COMSIG_MOD_ACTIVATE, PROC_REF(on_mod_activation))
 	RegisterSignal(mod, COMSIG_MOD_MODULE_REMOVAL, PROC_REF(on_mod_removal))
 	RegisterSignal(mod, COMSIG_ATOM_EMP_ACT, PROC_REF(on_emp))
 	RegisterSignal(mod, COMSIG_ATOM_EMAG_ACT, PROC_REF(on_emag))
 
 /obj/item/mod/module/dna_lock/on_uninstall(deleting = FALSE)
+	. = ..()
 	UnregisterSignal(mod, COMSIG_MOD_ACTIVATE)
 	UnregisterSignal(mod, COMSIG_MOD_MODULE_REMOVAL)
 	UnregisterSignal(mod, COMSIG_ATOM_EMP_ACT)
@@ -665,11 +673,15 @@
 	incompatible_modules = list(/obj/item/mod/module/plasma_stabilizer)
 	required_slots = list(ITEM_SLOT_HEAD)
 
-/obj/item/mod/module/plasma_stabilizer/generate_worn_overlay(mutable_appearance/standing)
+/obj/item/mod/module/plasma_stabilizer/generate_worn_overlay(obj/item/source, mutable_appearance/standing)
+	. = ..()
+	if (!.)
+		return
+
 	var/mutable_appearance/visor_overlay = mod.get_visor_overlay(standing)
 	visor_overlay.appearance_flags |= RESET_COLOR
 	visor_overlay.color = COLOR_VIOLET
-	return list(visor_overlay)
+	. += visor_overlay
 
 /obj/item/mod/module/plasma_stabilizer/on_equip()
 	ADD_TRAIT(mod.wearer, TRAIT_HEAD_ATMOS_SEALED, REF(src))
diff --git a/code/modules/mod/modules/modules_maint.dm b/code/modules/mod/modules/modules_maint.dm
index 989481af76c..3d4f17b7f7a 100644
--- a/code/modules/mod/modules/modules_maint.dm
+++ b/code/modules/mod/modules/modules_maint.dm
@@ -17,9 +17,11 @@
 	var/step_change = 0.5
 
 /obj/item/mod/module/springlock/on_install()
+	. = ..()
 	mod.activation_step_time *= step_change
 
 /obj/item/mod/module/springlock/on_uninstall(deleting = FALSE)
+	. = ..()
 	mod.activation_step_time /= step_change
 
 /obj/item/mod/module/springlock/on_part_activation()
@@ -149,18 +151,22 @@
 		return
 	SEND_SOUND(mod.wearer, sound('sound/machines/terminal/terminal_off.ogg', volume = 50, channel = CHANNEL_JUKEBOX))
 
-/obj/item/mod/module/visor/rave/generate_worn_overlay(mutable_appearance/standing)
+/obj/item/mod/module/visor/rave/generate_worn_overlay(obj/item/source, mutable_appearance/standing)
+	. = ..()
+	if (!.)
+		return
+
 	var/mutable_appearance/visor_overlay = mod.get_visor_overlay(standing)
 	visor_overlay.appearance_flags |= RESET_COLOR
 	if (!isnull(music_player.active_song_sound))
 		visor_overlay.color = rainbow_order[rave_number]
-	return list(visor_overlay)
+	. += visor_overlay
 
 /obj/item/mod/module/visor/rave/on_active_process(seconds_per_tick)
 	rave_number++
 	if(rave_number > length(rainbow_order))
 		rave_number = 1
-	mod.wearer.update_clothing(mod.slot_flags)
+	update_clothing_slots()
 	rave_screen.update_color(rainbow_order[rave_number])
 
 /obj/item/mod/module/visor/rave/get_configuration()
diff --git a/code/modules/mod/modules/modules_ninja.dm b/code/modules/mod/modules/modules_ninja.dm
index 5f7abdd712b..e75141cf3d5 100644
--- a/code/modules/mod/modules/modules_ninja.dm
+++ b/code/modules/mod/modules/modules_ninja.dm
@@ -93,11 +93,9 @@
 	required_slots = list(ITEM_SLOT_HEAD|ITEM_SLOT_EYES|ITEM_SLOT_MASK)
 
 /obj/item/mod/module/welding/camera_vision/on_part_activation()
-	. = ..()
 	RegisterSignal(mod.wearer, COMSIG_LIVING_CAN_TRACK, PROC_REF(can_track))
 
 /obj/item/mod/module/welding/camera_vision/on_part_deactivation(deleting = FALSE)
-	. = ..()
 	UnregisterSignal(mod.wearer, COMSIG_LIVING_CAN_TRACK)
 
 /obj/item/mod/module/welding/camera_vision/proc/can_track(datum/source, mob/user)
@@ -422,9 +420,11 @@
 	addtimer(CALLBACK(src, PROC_REF(boost_aftereffects), mod.wearer), 7 SECONDS)
 
 /obj/item/mod/module/adrenaline_boost/on_install()
+	. = ..()
 	RegisterSignal(mod, COMSIG_ATOM_ITEM_INTERACTION, PROC_REF(try_boost))
 
 /obj/item/mod/module/adrenaline_boost/on_uninstall(deleting = FALSE)
+	. = ..()
 	UnregisterSignal(mod, COMSIG_ATOM_ITEM_INTERACTION)
 
 /obj/item/mod/module/adrenaline_boost/proc/try_boost(source, mob/user, obj/item/attacking_item)
diff --git a/code/modules/mod/modules/modules_security.dm b/code/modules/mod/modules/modules_security.dm
index 06bd9352a9c..a19cd09db2b 100644
--- a/code/modules/mod/modules/modules_security.dm
+++ b/code/modules/mod/modules/modules_security.dm
@@ -22,6 +22,7 @@
 		guns_typecache = typecacheof(list(/obj/item/gun/ballistic, /obj/item/gun/energy, /obj/item/gun/grenadelauncher, /obj/item/gun/chem, /obj/item/gun/syringe))
 
 /obj/item/mod/module/magnetic_harness/on_install()
+	. = ..()
 	var/obj/item/clothing/suit = mod.get_part_from_slot(ITEM_SLOT_OCLOTHING)
 	if(!istype(suit))
 		return
@@ -29,6 +30,7 @@
 	suit.allowed |= guns_typecache
 
 /obj/item/mod/module/magnetic_harness/on_uninstall(deleting = FALSE)
+	. = ..()
 	if(deleting)
 		return
 	var/obj/item/clothing/suit = mod.get_part_from_slot(ITEM_SLOT_OCLOTHING)
@@ -135,6 +137,7 @@
 		balloon_alert(mod.wearer, "holster full!")
 
 /obj/item/mod/module/holster/on_uninstall(deleting = FALSE)
+	. = ..()
 	if(holstered)
 		holstered.forceMove(drop_location())
 
diff --git a/code/modules/mod/modules/modules_supply.dm b/code/modules/mod/modules/modules_supply.dm
index 3e9d47ebfb0..3eee7969e9c 100644
--- a/code/modules/mod/modules/modules_supply.dm
+++ b/code/modules/mod/modules/modules_supply.dm
@@ -422,7 +422,7 @@
 		mod.update_speed()
 	traveled_tiles = 0
 
-/obj/item/mod/module/ash_accretion/generate_worn_overlay(mutable_appearance/standing)
+/obj/item/mod/module/ash_accretion/generate_worn_overlay(obj/item/source, mutable_appearance/standing)
 	overlay_state_inactive = "[initial(overlay_state_inactive)]-[mod.skin]"
 	return ..()
 
diff --git a/code/modules/mod/modules/modules_timeline.dm b/code/modules/mod/modules/modules_timeline.dm
index 654aaa0e8ee..701cbc30421 100644
--- a/code/modules/mod/modules/modules_timeline.dm
+++ b/code/modules/mod/modules/modules_timeline.dm
@@ -20,10 +20,12 @@
 	var/true_owner_ckey
 
 /obj/item/mod/module/eradication_lock/on_install()
+	. = ..()
 	RegisterSignal(mod, COMSIG_MOD_ACTIVATE, PROC_REF(on_mod_activation))
 	RegisterSignal(mod, COMSIG_MOD_MODULE_REMOVAL, PROC_REF(on_mod_removal))
 
 /obj/item/mod/module/eradication_lock/on_uninstall(deleting = FALSE)
+	. = ..()
 	UnregisterSignal(mod, COMSIG_MOD_ACTIVATE)
 	UnregisterSignal(mod, COMSIG_MOD_MODULE_REMOVAL)
 
@@ -228,6 +230,7 @@
 	INVOKE_ASYNC(chrono_beam, TYPE_PROC_REF(/obj/projectile, fire))
 
 /obj/item/mod/module/tem/on_uninstall(deleting = FALSE)
+	. = ..()
 	if(!field)
 		return
 	field_disconnect(field)
diff --git a/code/modules/wiremod/shell/module.dm b/code/modules/wiremod/shell/module.dm
index bec6ce8e5c7..a3c1f8572ea 100644
--- a/code/modules/wiremod/shell/module.dm
+++ b/code/modules/wiremod/shell/module.dm
@@ -41,11 +41,13 @@
 	QDEL_LIST_ASSOC_VAL(action_comp.granted_to)
 
 /obj/item/mod/module/circuit/on_install()
+	. = ..()
 	if(!shell?.attached_circuit)
 		return
 	RegisterSignal(shell?.attached_circuit, COMSIG_CIRCUIT_PRE_POWER_USAGE, PROC_REF(override_power_usage))
 
 /obj/item/mod/module/circuit/on_uninstall(deleting = FALSE)
+	. = ..()
 	if(!shell?.attached_circuit)
 		return
 	for(var/obj/item/circuit_component/equipment_action/action_comp in action_comps)