'lolman? did you test your code?'

no i did not ms. kevinz

code/game/objects/items/RPD.dm

@@ -6,6 +6,7 @@ RPD
 #define ATMOS_CATEGORY 0
 #define DISPOSALS_CATEGORY 1
 #define TRANSIT_CATEGORY 2
+#define PLUMBING_CATEGORY 3
 
 #define BUILD_MODE (1<<0)
 #define WRENCH_MODE (1<<1)
@@ -75,6 +76,13 @@ GLOBAL_LIST_INIT(transit_tube_recipes, list(
 	)
 ))
 
+GLOBAL_LIST_INIT(fluid_duct_recipes, list(
+	"Fluid Ducts" = list(
+		new /datum/pipe_info/plumbing("Duct",				/obj/machinery/duct, PIPE_ONEDIR),
+		new /datum/pipe_info/plumbing/multilayer("Duct Layer-Manifold",/obj/machinery/duct/multilayered, PIPE_STRAIGHT)
+	)
+))
+
 /datum/pipe_info
 	var/name
 	var/icon_state
@@ -175,6 +183,15 @@ GLOBAL_LIST_INIT(transit_tube_recipes, list(
 	if(dt == PIPE_UNARY_FLIPPABLE)
 		icon_state = "[icon_state]_preview"
 
+/datum/pipe_info/plumbing/New(label, obj/path, dt=PIPE_UNARY)
+	name = label
+	id = path
+	icon_state = initial(path.icon_state)
+	dirtype = dt
+
+/datum/pipe_info/plumbing/multilayer //exists as identifier so we can see the difference between multi_layer and just ducts properly later on
+
+
 /obj/item/pipe_dispenser
 	name = "Rapid Piping Device (RPD)"
 	desc = "A device used to rapidly pipe things."
@@ -200,15 +217,19 @@ GLOBAL_LIST_INIT(transit_tube_recipes, list(
 	var/atmos_build_speed = 5 //deciseconds (500ms)
 	var/disposal_build_speed = 5
 	var/transit_build_speed = 5
+	var/plumbing_build_speed = 5
 	var/destroy_speed = 5
 	var/paint_speed = 5
 	var/category = ATMOS_CATEGORY
 	var/piping_layer = PIPING_LAYER_DEFAULT
+	var/ducting_layer = DUCT_LAYER_DEFAULT
 	var/datum/pipe_info/recipe
 	var/static/datum/pipe_info/first_atmos
 	var/static/datum/pipe_info/first_disposal
 	var/static/datum/pipe_info/first_transit
 	var/mode = BUILD_MODE | DESTROY_MODE | WRENCH_MODE
+	var/static/datum/pipe_info/first_plumbing
+	var/locked = FALSE //wheter we can change categories. Useful for the plumber
 
 /obj/item/pipe_dispenser/New()
 	. = ..()
@@ -256,11 +277,13 @@ GLOBAL_LIST_INIT(transit_tube_recipes, list(
 	var/list/data = list(
 		"category" = category,
 		"piping_layer" = piping_layer,
+		"ducting_layer" = ducting_layer,
 		"preview_rows" = recipe.get_preview(p_dir),
 		"categories" = list(),
 		"selected_color" = paint_color,
 		"paint_colors" = GLOB.pipe_paint_colors,
 		"mode" = mode
+		"locked" = locked
 	)
 
 	var/list/recipes
@@ -271,6 +294,8 @@ GLOBAL_LIST_INIT(transit_tube_recipes, list(
 			recipes = GLOB.disposal_pipe_recipes
 		if(TRANSIT_CATEGORY)
 			recipes = GLOB.transit_tube_recipes
+		if(PLUMBING_CATEGORY)
+			recipes = GLOB.fluid_duct_recipes
 	for(var/c in recipes)
 		var/list/cat = recipes[c]
 		var/list/r = list()
@@ -299,6 +324,8 @@ GLOBAL_LIST_INIT(transit_tube_recipes, list(
 					recipe = first_atmos
 				if(TRANSIT_CATEGORY)
 					recipe = first_transit
+				if(PLUMBING_CATEGORY)
+					recipe = first_plumbing
 			p_dir = NORTH
 			playeffect = FALSE
 		if("piping_layer")
@@ -469,16 +496,56 @@ GLOBAL_LIST_INIT(transit_tube_recipes, list(
 						if(mode & WRENCH_MODE)
 							tube.wrench_act(user, src)
 					return
-
+			if(PLUMBING_CATEGORY) //Plumbing.
+				if(!can_make_pipe)
+					return ..()
+				A = get_turf(A)
+				if(isclosedturf(A))
+					to_chat(user, "<span class='warning'>[src]'s error light flickers; there's something in the way!</span>")
+					return
+				to_chat(user, "<span class='notice'>You start building a fluid duct...</span>")
+				playsound(get_turf(src), 'sound/machines/click.ogg', 50, 1)
+				if(do_after(user, plumbing_build_speed, target = A))
+					var/obj/machinery/duct/D
+					if(recipe.type == /datum/pipe_info/plumbing/multilayer)
+						var/temp_connects = NORTH + SOUTH
+						if(queued_p_dir == EAST)
+							temp_connects = EAST + WEST
+						D = new queued_p_type (A, TRUE, GLOB.pipe_paint_colors[paint_color], ducting_layer, temp_connects)
+					else
+						D = new queued_p_type (A, TRUE, GLOB.pipe_paint_colors[paint_color], ducting_layer)
+					D.add_fingerprint(usr)
+					if(mode & WRENCH_MODE)
+						D.wrench_act(user, src)
 			else
 				return ..()
 
 /obj/item/pipe_dispenser/proc/activate()
 	playsound(get_turf(src), 'sound/items/deconstruct.ogg', 50, 1)
 
+/obj/item/pipe_dispenser/plumbing
+	name = "Plumberinator"
+	desc = "A crude device to rapidly plumb things."
+	icon_state = "plumberer"
+	category = PLUMBING_CATEGORY
+	locked = TRUE
+
+/obj/item/pipe_dispenser/plumbing/Initialize()
+	. = ..()
+	spark_system = new
+	spark_system.set_up(5, 0, src)
+	spark_system.attach(src)
+	if(!first_plumbing)
+		first_plumbing = GLOB.fluid_duct_recipes[GLOB.fluid_duct_recipes[1]][1]
+
+	recipe = first_plumbing
+
+
+
 #undef ATMOS_CATEGORY
 #undef DISPOSALS_CATEGORY
 #undef TRANSIT_CATEGORY
+#undef PLUMBING_CATEGORY
 
 #undef BUILD_MODE
 #undef DESTROY_MODE