Spacer for crooked gang box

My builder's electricians installed all of my gangboxes inconsistently, usually crooked and with varying depths. This causes problems when trying to install smart switches, fan switches, or any device whose surface you want parallel to the wall.  These spacers account for unevenly installed gangboxes; the inner surface matches the gangbox and the wall surface matches the wall. The spacer easily installs between the gangbox and the electrical device so you have a flat surface to mount your cover plate.  No more messing with small spacer tabs or standard parallel spacers.  Your device is straight, and the cover plate is snug to the wall.

To customize the spacer, use the depth gauge on a digital caliper to measure the depth from the wall surface to the front of the gangbox surface at all four corners. Record the four values as TL (top left), BL (bottom left), TR (top right) and BR (bottom right). In Fusion360, open the Modify\Change Parameters window for the desired gangbox size and update the User Parameters with your recorded values. The F360 model will create a cut plane through 3 of those points; if the wall surface and gangbox surfaces are perfectly flat planes, the cut plane will pass precisely through the 4th point. Sometimes the wall/gangboxes surfaces are not completely flat, but even then the 4th point should be close to the desired depth…accurate enough to be usable. Use your desired slicing program (i.e., PrusaSlicer) to create the custom Gcode for each spacer.  The "TOP" text should face up and toward you when you're installing the spacer.

I uploaded three example spacer files to visualize them, but you should modify the f3d files with your specific values, then slice them.

Settings:
Filament Prusament PLA
Nozzle 0.6
Layer 0.35mm
Supports no
Fill none
Perimeters 2
Temp 215C