Tying up the balls and/or the cock increases the pressure in a very hot way. After a while the area becomes extremely sensitive, and because the skin is stretched taut, a mere fingernail across it will be enough to make you scream!
Clothespins on the skin of your ball sack, neatly in a row, and I hope you can count them correctly? When I'm done, will I slap them all off at once, or will I remove them one by one at an agonizingly slow speed?
A ball crusher that is screwed tighter and tighter, perhaps during an interrogation scene as you are giving me the wrong answers?
I can suspend weights from your balls and/or cock with tweezer clamps or clover clamps. Their pinch can become quite nasty when you attach weights to them.
Ice cubes in your foreskin, right on top of your glans, and then I'll close up your foreskin with a clamp. Let's see how long you can handle that.
The list is endless, so I think it's better if you stop by sometime, so you can experience it for yourself.