Z ax stopper for "elektronik.si" Ultimaker, babushka style

I don't know about other Ultimakers, but that one has a long Z screw which is on rather springy coupling.

Because of that I got sometimes layer "missing" (second picture, before - after), so I design a cap for that screw.

You put in that cap 8 mm ball and a M3 screw on top. Then you just tighten the ball against the screw to reduce flexibility of that coupling.

I also included old version of that cap, which is bulkier.