None of the suggested printed buttons or default buttons really worked that well for me, but I found some that did. However those no longer had the source code available and were only available in select sizes, so I reversed engineered them and decided to upload the OpenSCAD file so that others won't run into this issue.
I may eventually adapt this into the 3 part buttons that print at a sturdier direction, but not in the immediate future.
Make sure you have BOSL2 installed: https://github.com/BelfrySCAD/BOSL2
Adjust the variables to your liking.
The author remixed this model.
All the buttons suggested on the Slimbox 2040 did not work for me. I found ones that fit really well but it did not have all the sizes available, so I reverse-engineered it and decided that I wanted to also upload the OpenSCAD file so no one runs into the same problem in the future.
The main difference is that āIā shaped prongs that ensure a snug fit and easy removal, despite the weaker printing angle.