Simple spacer for a UK light switch in a few variants. Designed for a Sonoff UK T1 switch but should fit other switches if you check the size first (the opening is 88mm in cad).
The CAD has a couple of parameters to tweak if you are so inclined.
The author remixed this model.
Needed a little more space for the switch side-to-side so created a new parametric cad based on the original