This is a decora style blank plate. It is an exact replica of an existing plate that I already had.
I will probably redesign it to optimize it for 3d printing.
With 19mm push button hole: https://www.thingiverse.com/thing:2794562
Update (2020/01/06): Uploaded the .step file.
Print front face on the print bed to have a smooth finish on the exposed side.
Use support for the top and bottom wings.