These are plungers, inserts, and surrounds for the standard Chinese LED arcade buttons that are common on Amazon, often branded under "Easyget," "Qenker," etc.

They most often come in sets of blue and red, and I found the blue buttons were really harsh when lit, not really filtering much of the white LED inside.

So I tried a couple of different methods of diffusing the light. One was just an insert to go between the plunger and inside of the button cap. Works, but really thin and hard to make look good. Then I tried the plunger, and first shot was a complete success (pictured).

The surround was just to get them to aesthetically match some of the other buttons I had on hand.