Summary

this can be used to replace a broken mixer valve diaphragm button. I bought a replacement once already, but it failed again, and now they are discontinued. This is designed to press in from the outside. make sure the bits of the old button have been removed. I used 85A TPU.

I also have a design posted for the mixer valve seal that fails eventually.
https://www.thingiverse.com/thing:6722754