When the patents expired, anyone could build a buckling spring keyboard.
A similar keyboard is described on this site in the review section, the "Mechanical Touch" keyboard. It wasn't an exact Model M clone; the springs were in cross-shaped wells rather than circular ones.
Due to problems with build quality, the keyboard, instead of being comparable to a Model M, was felt to be a poor quality keyboard, nearly unusable. It is possible, though, that with some modifications, like putting a rigid and flat insulating slab behind the membrane, it might be salvageable.