1 old beat up standard propane tank
Perlite (not vermiculite)
------ I used the burner from this instructable
High pressure gas regulator
Crucible (shown at end)
Reciprocating saw (for cutting the propane tank)
3" hole saw drill attachment (optional)
1 3/8" hole saw
Small drill bit
Step 1: Prep the Tank
Step 2: Cut the Propane Tank
Step 3: Drill the Large Exhaust Hole.
Step 4: (optional But Recommended) Lid Structure Addition
Step 5: Mix the Refractory and Cast
Mix 15.6 c Portland cement, 15.6 c perlite, 15.6 c sand, and 15.6 c wood ash. Thoroughly mix and add 33.5 c water. Then add 31.2 c Fireclay and mix until there are no dry pockets. It should be the consistency of very very very soft cookie dough. Pour it into the body of the tank and press a 6 inch diameter by 7 inch high cylinder (basically a large paint can) into the mix until it is right up to the top of the tank.
For the lid:
Mix .8 c Portland cement, .8 c perlite, .8 c sand, and .8 c wood ash. Add 1.25 c water and mix. Add 1.6 c Fireclay and mix. Before you pour the lid, find a 3 inch cylinder to put through the ventilation hole. I used a large spray paint can. Then pour the mix and pack it in, but be careful of the screws welded on!
If you have any leftover cement, make refractory bricks!
Step 6: Drill Gas Supply Hole
Step 7: Crucible
Step 8: Use It!
PS: if you don't have access to propane as fuel, you can use charcoal with a hair dryer blowing into it instead. It isn't as hot but still works for aluminum and other low melting point metals up to around 1400°F.