Version 2: Needed a way to easily remove and take it with me. This is a snug fit (with rubber feet) and the latches hold on firmly, so even one-handed XLR plugging in/out is no problem.
Version 1: This is an under desk mount for the Focusrite Clarett 2Pre. I measured my unit with 208x143x53 mm. With the rubber "feet" the height is 55mm. I did not want to remove them (glued in place), so I designed the bracket for a height of 55 mm and a depth of 143 mm - a tight fit.
I used 4 4x20 mm wood screws and designed the holes accordingly. The STL file represents the left bracket, the right one can easily be mirrored in the slicer.
Fitting the interface is facilitated by some flex along the sides. To screw the mount in place I placed the brackets onto the Clarett, positioned it and marked where the holes go. I screwed one bracket in place and fixated the front screw of the other. Then i slid the interface in - from back to front - while delicately bending the bracket. Once in place I put in the last screw and voilá.