[MIRROR] Makes material costs use sheets amount define (#12887)

Co-authored-by: Guti <32563288+TheCaramelion@users.noreply.github.com>
Co-authored-by: Cameron Lennox <killer65311@gmail.com>

code/modules/paperwork/pen.dm

@@ -26,7 +26,7 @@
 	w_class = ITEMSIZE_TINY
 	throw_speed = 7
 	throw_range = 15
-	matter = list(MAT_STEEL = 10)
+	matter = list(MAT_STEEL = MATERIAL_COST(0.005))
 	var/colour = "black"	//what colour the ink is!
 	pressure_resistance = 2
 	drop_sound = 'sound/items/drop/accessory.ogg'

code/modules/paperwork/photography.dm

@@ -132,7 +132,7 @@ GLOBAL_VAR_INIT(photo_count, 0)
 	item_state = "camera"
 	w_class = ITEMSIZE_SMALL
 	slot_flags = SLOT_BELT
-	matter = list(MAT_STEEL = 2000)
+	matter = list(MAT_STEEL = MATERIAL_COST(1))
 	var/pictures_max = 10
 	var/pictures_left = 10
 	var/on = 1

code/modules/paperwork/stamps.dm

@@ -9,7 +9,7 @@
 	slot_flags = SLOT_HOLSTER
 	throw_speed = 7
 	throw_range = 15
-	matter = list(MAT_STEEL = 60)
+	matter = list(MAT_STEEL = MATERIAL_COST(0.03))
 	pressure_resistance = 2
 	attack_verb = list("stamped")
 	drop_sound = 'sound/items/drop/device.ogg'