If this is the same video we're talking about, he 'just' melted down the beer cans into a block of aluminum and then machined a lower from it, right? (and he also made a video where he melted down spent brass and machined an AR lower from it) If so, that melting down can be done using $15 of home depot materials (metal bucket, thermal insulation wool or cement, 2 propane burners)

(DIY metal smelting/foundries are a great way to waste a few hours watching Youtube videos)