My PROPANE (!) Foundry
It fits pretty well in my helium tank foundry/furnace (a .gif on how I made it is below), heating it up to melting temps on full blast in probably <10 minutes. It is SO much cleaner, easier to make multiple melts( no refilling charcoal), and is alot quicker in starting and finishing a melt (no setting up blowers, positioning charcoal, and that stuff).
It was (at first) an easy choice to go with charcoal (cheap, could even be made for free), but after a couple melts, the fun got replaced by work, and I stopped melting metal. I discovered propane, built my burner for $35 total(including regulator) and was up and running within a day.
~$20 for a refill on propane when I run out is COMPLETELY worth it.
Sorry if this seems kinda persuasive, but I am trying to help either people on this site, or one of the countless wanderers from Google.
Some pictures of my testing (not my burning setup) setup are below.