Bet they could be made in a 3D printer
I have a clear cap bought many years ago, also have a cut cap. It's a real kick to watch those sparks fly at night.
These folks are amazing. I never would have thought to cut a cap like this to see inside a running car. This is an A+++ shade-tree idea. Thanks.
Picture gluing a clear thread together over and over. That is what 3D printing would look like. The solution type of 3D printer might work. But who's going to program it? To make a few it would be easy to make a mold and cast it.I thought of the 3D printer idea but most people familiar with 3D printers say the piece would not hold up and probably wouldn't work anyway.