Better start slow, you don’t want to scare him off! See if he is comfortable if you are being a bit rough with his jewels, and if not: respect his decision!
Maybe I'll try a sandbag or one filled with rice, peas or whatever. That's definitely more comfortable than a hard ball. I think it depends on the mass and the speedwith which the balls are hit.
I'll have to ask my professional dominatrix. I don't feel the right pain from the compression that my wife does. 250g is really a lot. I thought you had sand or something like that in your stocking. That could be good too. Thank you for your answer.