For use in pinball machines with launch buttons. There are a few variations of the launch buttons, I didn't find any online for this type.
The graphic/diffuser plate can be used with regular white printer paper, do a circle that's 47.5 mm in diameter. Or cut vinyl and apply on the plate.

Meassured and modeled by myself, fits great with my launch button. Personally I think this looks better than the one included when bought, light gets a bit brighter and better diffused.

I printed mine with white Bambu PLA matte.