Phone post so bear with me. Anyway yes it’s metal but it’s baffeled. Basically, you just need about 6 juicy juice cans. The bottom one, you drill a hole at the bottom for the fuel and cut the top of the bottom one 1/2way out, basically a d shape. Then, the 2nd to bottom can till the next to top can, you cut the d’s alternating, so the charge builds more compression as it comes out. The top can you cut a d in the bottom and cut the top open so you can load it. Make sense at all? I’ll post some pics saturday, it’s very easy.