So i just did an amateur session with a plexi glass ball crusher. Basically one of these:

https://ballbustingtoys.com/products/basic-adjustable-cbt-testicle-crusher-vice

Not sure where this has been all my life. But damn i didnt know you could get your balls so flat. They might as well have been pancakes. And the pain was incredible. Started in my gut and by the time it had really clamped down i could feel it in my neck and face so obviously was hitting all sorts of nerves. Every time she would clamp down further the pain would ratchet up then my body would adjust the pain would subside and then a further clamp would send me right back down that tunnel of pain. It was a consistent throbbing pulsing pain. And by the end i was just scared to move. I don’t beg to stop often but this one pushed the right buttons and brought me to my knees. Fun times.

This is great!! Not too long ago, we were all stuck with making our own. Thanks for posting this site. I will be doing some online shopping over the weekend.

This is an alternative
https://www.extremerestraints.com/the-cock-and-ball-crusher-board.html

I suspect yours is cheaper and better.