Previously I thought the only way to get an FD lens to work was with an adapted which would either not allow focus to infinity or require an extra lens element to correct focus.
Then I came across these expensive things online. (one site:
http://fdtoef.com/ ) (There's a few different sites)

Which require dismantling part of lens and also applying a little arm so that the aperture works, said to be completely reversible.
These are a bit over 100 bux a pop, and I'm not sure why there's different ones for different lenses, whether it's just for the detector pins.
MY QUESTION:
Has anybody had any experience making their own?
Either CNCing or machining metal (whichever the correct term is).
OR
3D printing in a nice black plastic?
If not, is anybody an experienced 3D modeller willing to make a free printable model?
(Not that I have a 3D printer, but I have enough FD lenses that a 3D printer would be worth buying).
That's if plastic would be reliable enough.