If forty years ago, a Viet Cong in a backwater jungle blacksmith shop can turn out usable 30 round magazines for captured M-16s with just some sheet steel and tin snips what chance does a ban have?
Absolutely freakin’ none, especially when there’s loads of Americans equipped with hydraulic presses which can be used to press halves of magazines from sheet steel or aluminum... which we then glue or weld together with a TIG rig.
Add some coiled music wire, mold a follower from aluminum of pot metal, and you’re done. Wha-la. Magazine in a garage shop - by the dozens if you want them.
All you need to do is make the fixtures and dies onto which you put the sheet metal for bending in a press.