I used mine for almost 3 years now and it showed minimal wear :)
you will need 3 more things besides the 3D print.
- 6mm steel ball
- steel spring 10mm long with outer diameter 5mm
updated "inner piece" 11/30/2019 : deeper holes for the mechanism so that there's less wear and tear.
glue the spring mechanism inside the hole to not make it shoot out when the case is pulled apart.
the logo is supposed to just snap inside and be held by friction. if it doesn't work you can use the one with a bigger tollerance and glue it in place.