Made tanks empty, remove unnecessary tank types and added toxins tech requirement to AEG and welding gas mask

code/game/objects/items/weapons/tanks/tank_types.dm

@@ -27,6 +27,9 @@
 			to_chat(user, text("<span class='danger'>The meter on the [src.name] indicates you are almost out of air!</span>"))
 			//playsound(usr, 'sound/effects/alert.ogg', 50, 1)
 
+obj/item/tank/oxygen/empty/New()
+	..()
+	air_contents.oxygen = null
 
 /obj/item/tank/oxygen/yellow
 	desc = "A tank of oxygen, this one is yellow."
@@ -142,11 +145,19 @@
 			to_chat(user, text("<span class='danger'>The meter on the [src.name] indicates you are almost out of air!</span>"))
 			user << sound('sound/effects/alert.ogg')
 
+obj/item/tank/emergency_oxygen/empty/New()
+	..()
+	air_contents.oxygen = null
+
 /obj/item/tank/emergency_oxygen/engi
 	name = "extended-capacity emergency oxygen tank"
 	icon_state = "emergency_engi"
 	volume = 6
 
+obj/item/tank/emergency_oxygen/engi/empty/New()
+	..()
+	air_contents.oxygen = null
+
 /obj/item/tank/emergency_oxygen/syndi
 	name = "suspicious emergency oxygen tank"
 	icon_state = "emergency_syndi"
@@ -158,6 +169,10 @@
 	icon_state = "emergency_double"
 	volume = 10
 
+obj/item/tank/emergency_oxygen/double/empty/New()
+	..()
+	air_contents.oxygen = null
+
 /obj/item/tank/emergency_oxygen/double/full
 	name = "pressurized double emergency oxygen tank"
 	desc = "Used for \"emergencies,\" it actually contains a fair amount of oxygen."

code/modules/research/designs/equipment_designs.dm

@@ -115,7 +115,7 @@
 	name = "Welding Gas Mask"
 	desc = "A gas mask with built in welding goggles and face shield. Looks like a skull, clearly designed by a nerd."
 	id = "weldingmask"
-	req_tech = list("materials" = 2, "engineering" = 3)
+	req_tech = list("materials" = 2, "engineering" = 3, "toxins" = 3)
 	build_type = PROTOLATHE
 	materials = list(MAT_METAL = 3000, MAT_GLASS = 1000)
 	build_path = /obj/item/clothing/mask/gas/welding

code/modules/research/designs/misc_designs.dm

@@ -92,91 +92,41 @@
 	category = list("Miscellaneous")
 
 /datum/design/emergency_oxygen
-	name = "Emergency Oxygen Tank"
-	desc = "Used for emergencies. Contains very little oxygen."
+	name = "Empty Emergency Oxygen Tank"
+	desc = "Used for emergencies. Onl contains very little oxygen once filled up."
 	id = "emergencyoxygen"
 	req_tech = list("toxins" = 3)
 	build_type = PROTOLATHE
 	materials = list(MAT_METAL=500, MAT_GLASS=100)
-	build_path = /obj/item/tank/emergency_oxygen
+	build_path = /obj/item/tank/emergency_oxygen/empty
 	category = list("Miscellaneous")
 
 /datum/design/extended_oxygen
-	name = "Extended Emergency Oxygen Tank"
-	desc = "Used for emergencies. Contains a decent amount of oxygen."
+	name = "Empty Extended Emergency Oxygen Tank"
+	desc = "Used for emergencies. Can contain a decent amount of oxygen once filled up."
 	id = "extendedoxygen"
 	req_tech = list("toxins" = 4)
 	build_type = PROTOLATHE
 	materials = list(MAT_METAL=800, MAT_GLASS=100)
-	build_path = /obj/item/tank/emergency_oxygen/engi
+	build_path = /obj/item/tank/emergency_oxygen/engi/empty
 	category = list("Miscellaneous")
 
 /datum/design/double_oxygen
-	name = "Double Emergency Oxygen Tank"
-	desc = "Used for emergencies. Contains a good amount of oxygen."
+	name = "Empty Double Emergency Oxygen Tank"
+	desc = "Used for emergencies. Can contain a good amount of oxygen once filled up."
 	id = "doubleoxygen"
 	req_tech = list("toxins" = 5)
 	build_type = PROTOLATHE
 	materials = list(MAT_METAL=1500, MAT_GLASS=200)
-	build_path = /obj/item/tank/emergency_oxygen/double
+	build_path = /obj/item/tank/emergency_oxygen/double/empty
 	category = list("Miscellaneous")
 
 /datum/design/oxygen_tank
-	name = "Oxygen Tank"
-	desc = "A large oxygen tank."
+	name = "Empty Oxygen Tank"
+	desc = "A large, empty air tank."
 	id = "oxygentank"
 	req_tech = list("toxins" = 5)
 	build_type = PROTOLATHE
 	materials = list(MAT_METAL=3000, MAT_GLASS=500)
-	build_path = /obj/item/tank/oxygen
+	build_path = /obj/item/tank/oxygen/empty
 	category = list("Miscellaneous")
-
-/datum/design/emergency_nitrogen
-	name = "Emergency Nitrogen Tank"
-	desc = "Used for vox-related emergencies. Contains very little nitrogen."
-	id = "emergencynitrogen"
-	req_tech = list("toxins" = 4)
-	build_type = PROTOLATHE
-	materials = list(MAT_METAL=500, MAT_GLASS=100)
-	build_path = /obj/item/tank/emergency_oxygen/nitrogen
-	category = list("Miscellaneous")
-
-/datum/design/nitrogen_tank
-	name = "Nitrogen Tank"
-	desc = "A large nitrogen tank."
-	id = "nitrogentank"
-	req_tech = list("toxins" = 5)
-	build_type = PROTOLATHE
-	materials = list(MAT_METAL=3000, MAT_GLASS=500)
-	build_path = /obj/item/tank/nitrogen
-	category = list("Miscellaneous")
-
-/datum/design/vox_tank
-	name = "Vox Specialized Nitrogen Tank"
-	desc = "A high-tech nitrogen tank designed specifically for Vox."
-	id = "voxtank"
-	req_tech = list("toxins" = 6)
-	build_type = PROTOLATHE
-	materials = list(MAT_METAL=2500, MAT_GLASS=500)
-	build_path = /obj/item/tank/emergency_oxygen/vox
-	category = list("Miscellaneous")
-
-/datum/design/emergency_plasma
-	name = "Emergency Plasma Tank"
-	desc = "Used for plasmaman-related emergencies. Contains very little plasma."
-	id = "emergencyplasma"
-	req_tech = list("toxins" = 5, "plasmatech" = 2)
-	build_type = PROTOLATHE
-	materials = list(MAT_METAL=500, MAT_GLASS=100, MAT_PLASMA = 50)
-	build_path = /obj/item/tank/emergency_oxygen/plasma
-	category = list("Miscellaneous")
-
-/datum/design/plasma_tank
-	name = "Plasma Tank"
-	desc = "A tank of plasma."
-	id = "plasmatank"
-	req_tech = list("toxins" = 5, "plasmatech" = 3)
-	build_type = PROTOLATHE
-	materials = list(MAT_METAL=3000, MAT_GLASS=200, MAT_PLASMA = 500)
-	build_path = /obj/item/tank/plasma
-	category = list("Miscellaneous")

code/modules/research/designs/weapon_designs.dm

@@ -6,7 +6,7 @@
 	name = "Advanced Energy Gun"
 	desc = "An energy gun with an experimental miniaturized reactor."
 	id = "nuclear_gun"
-	req_tech = list("combat" = 5, "magnets" = 5, "powerstorage" = 5)
+	req_tech = list("combat" = 5, "magnets" = 5, "powerstorage" = 5, "toxins" = 5)
 	build_type = PROTOLATHE
 	materials = list(MAT_METAL = 10000, MAT_GLASS = 2000, MAT_URANIUM = 3000, MAT_TITANIUM = 1000)
 	build_path = /obj/item/gun/energy/gun/nuclear