Does anyone have a video or some specific knowledge to share?

Specifically; I'm interested to find out how replacement Pop Caps are made for the early Bally Solid State popcaps.

Example:
c/o MarcoSpecialties.com
https://www.marcospecialties.com/pinball-parts/A-3713-44

I seem to vaguely recall watching an older video with an older gentleman hot stamping the top "design" on the the popcap.
But I don't recall where I saw it... or if the video covered the triangular paint design. TBH; looking at some burn out caps here; I'm pretty sure they triangular pattern is applied with some kind of mask and some kind of spray paint because of the amount of overspray (seen in the corners) I've seen on these caps.

Does anyone know for sure?
http://pbresource.com/pfbumper.htm seems to indicate the caps came in Red, Blue, Green, Yellow, and Black.
I'm pretty sure I saw at least one instance of a naked white cap with no art.

I'm sure it's a trade secret; but I wonder out loud who actual does the art on the game specific caps. I'm imagining a lot of work to replicate the art packages of all these games.

You can't ink as the mold is injection molded. Pressures are too high, too hot. Has to be done after the fact

Humm... off to google...