I needed a way to mount an ATX power supply to the underside of my desk.
For the basic setup, three components:
Print 4x vertical brackets, 2x of each arm - note every component should be printed flat. I recommend CA-gluing all the parts in place to make your installation easier.
Once it's screwed in place it is very sturdy - I had this version in use for over a year. See github link for Fusion file and the janky PDU version: https://github.com/christrotter/3d-models/tree/main/functional/under-desk-atx-mount
The author marked this model as their own original creation.