I updated the design to use parameters to determine the height of the pillars and depth of the nuts, the original design did not work with the standard length of screws.
I purchased an upgraded PSU for my A8 replacing the 20A for a 30A unit.
Unfortunately the mounting holes on the new supply did not line up with the existing holes and a didn't want to drill new ones.
The PSU has M5 (5mm) mountings, but I didn't have any M5 screws the correct length.
There are 4 M3 screw threads in the corners of the PSU but they only allow the screws to a depth of 1.5mm.
It took me a while to work out the exact positions of the holes which you can see in the diagram.
I printed the design and it worked, I could have adjusted the depth the recess for the M3 nuts but it worked and I have not bothered to changes the design.
I used Fusion 360
Insert the M3 nuts into the 4 inner positions
If they are tight used a soldering iron to warm them up and they will easily push into position
I used the A8 CAD drawing
I downloaded the A8 CAD drawing and used the measurement tool in Fusion to find out the distances between the original PSU mounting holes
30A 12v 360w psu