This thing is two printed clips that snap very securely into 1.5" 8020 and hold the controller module at a 45 degree angle.
Printed with ABS, 0.25 mm first layer, 0.2mm remaining layers, 30% infill. I applied Velcro tape to each clip and the back of the controller box so it can me moved as needed.
This design is a mash-up of my camera mount and improved 8020 clip profiles. The clips snap into the top and side slots in the 8020 extrusion. These things hang on so tightly you'll have to use a screw driver to reposition them.