Replacement back plate for BTT (Big Tree Tech) Smart Filament Sensor including a simple one-side mounting for M4 fasteners.

Provides 2x M4 slots on one side, suitable to mount on an aluminium extrusion.
Supports fastener spacing from 12.5mm to 32.5mm.

STL and STEP are provided in case you want to modify. The backing plate I've modelled from scratch using a real part and the manufacturer-provided STLs as reference. Tested and fits well.

Depending on position of fasteners, may require removing the tube fitting from one side to access. For mounting on a rail with T-nuts, just position the offending fastener at the end of the slot where it can be accessed without removing the tube fitting.

Model measured from real part, and checked against BTT's STL files for accuracy. Test fit off my printer is good.

The counterbore holes I've expanded slightly for better clearance once printed (6mm CB and 3.5mm thru).

Side mount holes are 4.5mm slots x 10mm length x 22.5mm spacing. This should allow fitting to 20x20 or 30x30 aluminium extrusion with T nuts and M4 fasteners.