I wanted to mount my ThinkCenter 720q mini pc to the French cleat wall in my den. Not finding anything suitable, I designed this one in Fusion 360 and printed it. Does exactly what I needed.  It could be a bit tighter, so if it is printed, maybe reduce the overall height between top and bottom (the long brackets that clip the PC) by about 1mm.

Printed at 50% infill and Grid support for the small overhang on the top and bottom center extensions (that clip the PC into the mount). About a 7h25m print time.