Should make robots unable to build anything out of plasteel and only plasteel. Here's hoping.

code/game/objects/items/stacks/stack.dm

@@ -34,6 +34,10 @@
 /obj/item/stack/attack_self(mob/user as mob)
 	list_recipes(user)
 
+/obj/item/stack/sheet/plasteel/cyborg/attack_self(mob/user as mob)
+	user << "<span class='warning'>You lack the subroutines necessary to build more complex structures with that material.</span>"
+	return
+
 /obj/item/stack/proc/list_recipes(mob/user as mob, recipes_sublist)
 	if (!recipes)
 		return
@@ -272,4 +276,4 @@
 	New(title, recipes, req_amount = 1)
 		src.title = title
 		src.recipes = recipes
-		src.req_amount = req_amount
+		src.req_amount = req_amount