I have balls weighting 170g (pool), 400g (Stone) and 670g (petanque game ball), the smaller ones from up to 1m, the petanque maximum 50cm as there is a risk of testicle rupture beyond that. Note that the balls are on an "anvil", nowhere to go.

I used to have, but was deleted by the platform where I had it.

It does, occasionally even "beat my ejaculation out", when I was close enough to cumming before the ball fell!

Of course its a question of raising intensity slowly, following the spiraling up of arousal and to not go overboard, so pain completely overcomes arousal.