I designed this thing in OpenSCAD though I did borrow a few elements from another recent model so that I could use 5/8″ #4 screws. The bottom where the screws go in is set to a height that allows the screws to go in just under 1/4″ which is enough to hold, but not enough to go through the material they’ll be screwed into. This is one of the things I love about making custom mounts and brackets, you can configure them to match the hardware you have available.
With many of the things that need (semi) precise placement of things, it takes two to three revisions to get it right. I actually used the second revision because I was in a hurry, but I’ve modified the file so version 3 will be just right next time. (I had the panel mount screw holes just a little too close together. Things flex enough that it works, but it could be better, and will be… next time.)
The first version actually warped quite a bit in printing. It’s a problem we seem to have occasionally with the old MakerBot. It’s always the front left corner of the print. I find that by shifting the print on the bed to the right just a bit often fixes the problem (at least for small prints.)