This is a replacement for an SGI O2 with the bigger metal base-plate/cage for MIPS 10K or 12K CPUs.
If you're lucky to find a complete 10K/12K cage to upgrade your 5K O2, most of the time the plastic tray is missing or broken.

This is a replacement based in the tremendous work of user joshyfishy22 from the sgi.sh forum who designed the base model for a 5K CPU tray.
I stretched the backplate and removed unneeded surfaces which would just eat up filament.

After printing it in PLA with 0.2 layer hight on my Bambulab P1S the tray fits perfectly and needs to be printed with supports.

Nota bene: PLA is too weak to handle the force of the Push-Pull-Lever. While it fits and moves like a charm, the weak'ish PLA neither can't stand the force when levering to press the board it in or pull it out nor will it sturdy enough to take the screw to fixate the lever.
So for my O2 I left it out and skipped the thoughts how to ever get that thing out of the case again :-/
Other filament or sinking a (tiny) tread might work, though.