Thai cocoa milk cans as one-off casting molds: You can't get much cheaper than that! Just cut side top open with tin snips, rip apart with a pair of pliers. Al shrinkage when cooling makes mold release dead easy! Top surface porous/ dirty app 2 mm down - just cut off a 10 mil slice as an ingot for another melt. 70 mm dia and 100 mm height makes excellent pieces for turning. Filled to the brim, it equals 1 kg of FREE-cutting Al alloy! But Hey! - not just ANY aluminium will do! -No sheet, tubes, rods, kitchenware of pure Al (nor any extrusion alloys!) in this Cheapos's pot! Maybe I'll even try those by tossing in 0.5% lead/ antimony each (.22 bullets) into the melt to reduce smear/ hogging when machining/ improve chip breaking? Below: DIY fireproof ceramic stand-off from the refractory leftovers.