Thanks for your reply and feedback, YoGaBaR. Interesting that you said you wanted lit purple buttons. I also want lit purple buttons for one of the player controls on my 4-player control panel, however I have not been able to find any concave translucent purple buttons anywhere. Have you come across any? I've even posted a topic about it, but have gotten few responses.
There are solid purple, and some translucent convex 24mm and 30mm purple buttons, but no translucent 28mm concave purple buttons. The only option suggested is to use clear buttons with an RBG to create purple. I also wonder if a blue button with a red light (or vice-versa) would create a decent purple? What have you done to create lit purple buttons?