I decided to post a FR at kicad launchpad
This is something I already addressed in the past…
It would be very useful IMO to add the ability to assign an ‘opacity’ value to 3D models for the 3D viewer. This option could be just 4 values like 0,0.25,0.75,1 so to be able to specify the transparency of the 3D model (from invisible=0, to completely opaque=1).
This feature would be very useful for mechanical design involving for examples enclosures.
This is how it could be added to the 3D preferences dialog:
Please feel free to comment or make suggestions.