Material list:
4 hoppers
2 DISPENSERS
1 DROPPER
(THERE IS A DIFFERENCE)
1 non-flammable slab
1 barrel (can be replaced with a double chest)
1 solid block (oak planks)
1 bucket of lava
2 observers
2 Redstone torches
14 non-flammable blocks (glass recommended it just looks nice)
A good bit of easily breakable blocks (scaffolding) (temporary)