Print the Test to see which size studs will hold Lego bricks best. Even a new filament can affect how bricks will stick. Either will probably work for your printer, but for best fit, print the test.

After you figure out which size to use, then figure out if you want a solid switch plate or one that is shelled. The shelled one will require support material and probably bridging. Spin the models around to see what the back looks like. The good news is that the supported surface will be against the wall.

Remove the switch plate you plan to replace and look to see if the switch box is completely inside the wall. If it is, print the solid switch plate. If screws or the box sticks out from the wall some, print the shelled version; it will fit better against the wall.

Print instructions

Category: Decor Print Settings

Printer Brand: Prusa

Printer: i3 MK2S

Rafts: Doesn't Matter

Supports: Yes

Resolution: .2mm layers

Infill: Any

Notes:

Support and possibly bridging might be necessary for the shelled versions. Look and rotate the models to see which one you want.

The studs are slightly different sized, so print the test to see if brinks stick better for the smaller size or not.