Based on what I see of his fabbed stuff, I'd suspect that he's got a good cutting device (maybe a shear,) and a decent press brake.
Unless I'm looking at the wrong part (
https://www.ebay.com/itm/361231747212,) it'd probably take him some time to fabricate one. The original part looks like it's made in a press as a single piece (probably a couple of strikes on different die sets.) If you're going to make this out of sheet, there are at least 3 sets of pieces (a flat plate for the bottom, and a pair for each set of sides,) and the hole at the bottom wouldn't be dressed as nice. Even with a good TIG and a jig setup, you're probably looking at an hour or more just in stitching time.