There is no loophole.
A decent machinist will be able to create an untracked receiver until you have strict controls over machine tools. Even if you don't distribute 90% ones, they're just not that hard to machine. Even without a 90% one distributed, you can either machine it down from a solid block --- I've never tried making one, so that might be a little tedious --- or 3D print a 90% one and use that for lost wax/pla/whatever mould.
I've tried out the latter process, and it's pretty straightforward. If you're using poster of paid for the slip, then the main difficulty is not overheating the mould when you're burning out the plastic. That's quite tricky in a Gingery furnace. A Gingery furnace is the kind of backyard foundry anyone can build with even basic supplies. So if you have one, you'll probably want something other than plaster of Paris, like better investment casting or go for sand casting instead. That has reusable moulds (so less need for a 3D printer)* but less precision, so more finishing is needed.
Or if you have one, use a temperature controlled kiln. Or if you don't, you can build one. I've not tried that, but there are instructions i the interwebs. Mostly it involves gently filing channels in firebricks and inserting coils of wound nichrome wire. I'm not going to try that. Old kilns can be had reasonably cheap and it's not like I have anywhere to put one anyway.
However I hear that a graphite crucible, an inanimate carbon rod and an arc welder make for a service arc furnace for melting stuff with none of the faff of charcoal and air blowers like the Gingery furnace. All available on eBay cheap. I'm going to try that soon.
* yes yes I know you can do lost wax without a 3D printer, but you still need some way of making the moulds a and a 3D printer is a fantastic way of churning out repeatable, disposable moulds.