Silicon Carbide Wine Bottle Crucible Mold.

Inspired by @ShakeTheFutur_300416, I tried out his version but it didn't work for me: https://www.printables.com/model/458620-silicon-carbide-crucible-mold

Instead, this one uses a flat bottom (no punt) 750ml wine bottle cut 100mm tall.  This should be a standard size, and free or cheap, which is why I chose it, and and there are many methods you can use to cut a wine bottle.  I used a tile saw, google for other options.

The jig goes in the bottle and you can fill it with 500 grit silicon carbide powder to find out how much you need (about 240 grams), then measure by weight and add it to a plastic ziplock with 10% sodium silicate as per @ShakeTheFuture_300416's instructions (check his Patreon).

Once mixed, you fill the bottom of the bottle with about 5mm of the mixed composition, then pack it down with the 50mm sand ram.  Then add the jig and use the ram to pack it down very well in about 3 layers.

Once done, put it in the freezer for an hour or so.  The jig has a 2 degree draft angle, but it might still be hard to remove, though mine did come loose once frozen on the first try.  I've also included a small hole that runs through the center of the jig to the bottom, you can try to blow some compressed air in that hole to loosen it.  A good idea is to get a basketball filler needle and heat it up and press it in the hole so you can attach a pump.

After, follow his instructions to cure the crucible - I haven't done this yet, still waiting to get to Ikea for a microwave.

I've included the Fusion 360 files here, feel free to remix, I'd love to see what you come up with.