Two more options for mounting the ThirdReality Motion Sensors or Smart Buttons.
Both of these are for flat surface mounting, one with 3M VHB tape or Command Strips, the other with a small screw.
Tape Mount:
https://www.printables.com/model/377327-thirdreality-motion-sensor-or-smart-button-flat-su
Screw Mount:
https://www.printables.com/model/377341-thirdreality-motion-sensor-or-smart-button-flat-su