The original design did not fit the HP Eliteone 800 G2 AIO. Even though at first glance it looks compatible. The diameter on the base is different. I'm not sure what other models use this smaller size, but I'm sure it's not a once off.
Honoredtwig's design allowed you to use a regular 8mm screw. I've included different lengths, so you can use 5 or 6mm screws (commonly used for PCs). A washer if you have a 4 or 5mm caphead screw. And a 5mm countersunk screw version, which is what we had on hand.
This has been designed in OnShape if you need to make modifications
The author remixed this model.
Re-created design. Smaller base and various sizes, and support for countersunk screw