This is my take on a 10" server rack, fully 3D printed and designed to be as slim and compact as possible.
 

I decided to use only RackStuds (printed flat for extra strength) to make the rails sturdier and easier to work with.

The Rackstuds are from this project by eirikjeppesen but I've included them in my project file for ease of printing and completeness.
 

The entire rack is held together using dovetail-mounted side panels and top/bottom brackets, secured with 3D-printed bolts.
To keep things simple, the bolts and RackStuds nuts are the same size. I’ve also included a small key I made for personal accessibility reasons, it helps tighten everything more easily, and a key with threads to help clean the ones on the parts, I haven't needed it but I thought it was better to have it than not.
 

The current setup features 5U rails, but it should be possible to stack more units by using taller side panels and reinforcing the structure with a 2U panel at the back (or front). If the model gets some interest—or if I end up needing to expand—I’ll design and test that out too.
 

All parts were printed in PLA+, and so far, I haven't had any issues.
 

In the photos, you can see a simple switch mount and a 1U module that holds three Raspberry Pis 4B. It uses sliding drawers designed for Pis with a passive heatsink, PoE HAT, and a 40mm rear fan. If there’s interest, I’m happy to upload those models as well!