Not certain why you'd need to lube adapters, as they'd be a stationary part -- attaching to the alps mount on the switch, and the MX mount on the cap, essentially just becoming part of the cap. Are you worried about them being a tight fit into the cap?
3D printing quality can vary widely based on the specs of your printer and the type of plastic used. In my experience, I've had prints come out too small, rather than too large, so filing wouldn't be much help either.
I'm not aware of any attempt at a group buy for such an adapter. I think the trick would be getting a high enough order quantity to finance the production and testing of a mold while still keeping the price per adapter low enough that people are willing to pay it. And if it did go through, you'd likely end up with a huge number of adapters to sort, pack, and ship.
If you're really just looking to get a set for yourself, and you have access to a decent 3D printer, it's probably worth trying a print or two and seeing how it turns out.