I got frustrated with the lack of springiness in the stock Mendel90 Z endstop holder, since I didn't have any rubber rings or such to put in there. It also didn't have enough range of motion to my liking. So I set out to change both.
Later the same day, I've made some more reinforcements and printed a perfectly functional version. Enjoy, all!
Uses parts of the original Mendel90 Z-endstop holder model.
I used a long M3 screw, a ballpoint pen spring, a nut and washer and the 2 printable parts included in this thing. It's fairly simple to put together, but you might have to sand down the sliding rod.. it's got a tolerance of 0.5 mm.