High profile bracket for Nvidia Quadro p400. The mounting screws cut threads into the plastic. First wanted to add nuts, but I don't think it is needed.

Embedded cylinders for extra rigidity, it really helps with holding GPU in a place without flexing. The bottom cylinder additionally holds PCB.

I use Quadro in headless mode and I don't have mini dp cables to test if it still fit, please report your results in comments.

Recommended filament PETG or ABS. PLA should be fine as p400 doesn't really get hot, but I would just go with PETG to be safe.

Cylinders don't need additional supports. Just change Support Overhang Angle to a very high number like 80° to remove them. If my first gen Ender 3 can print them without support, you should have any problems.