is this the crucible?....
The crucible in the piece was a commercial made one that looked cast, no welding, just a cover and everything else. Time is money, but I believe the Brownells crucible can be cobbled up pretty quick and easy, at least a fellow might be paying themselves a hundred bucks an hour to come up with something close.
Mine looks about the same. Instead of rings for the tongs, I just cut four v's off some angle iron with a chop saw and welded them on the sides, then the tong jaws go in between. For the cover, I decided to use a threaded pipe cap, and a grinder to clear out the threads for a slip fit. The only thing I'd do different that may not be a bad idea is some way to get the base off the kiln floor a little bit.
I've used stainless heat treat foil a bunch of times for other things. A little scrap of paper will consume any oxygen in there. A good consideration is to double wrap and burnish it down tight, but don't be surprised if some sharp corner pokes a hole in it.
I believe what happens somewhere around 133-something degrees is that steel looses magnetism. I believe that's the bare minimum change required for the steel to harden. Interesting thing, on the way up in temp, the point it becomes non magnetic is very precise, but on cooling back down, I know for myself that steel will stay non magnetic till quite a bit cooler and it will regain magnetism over a broad temp range.
I believe that is part of what's going on when there is an intentional delay between pulling the crucible from the oven and quenching. Maybe the 'art' part of it is the insulation of the crucible and charcoal on the slight cooling of the part, and the unevenness of the cooling of the part, just before it hits the quench.
