I have a little game I play where I take a bunch of random porn pictures and use that as a sort of a "queue" for nipple torture. This relies on the clamps being connected by something like a chain, personally I use clover clamps for reasons that will become apparent later.
First you need a bunch of random pictures obviously. In these you should include things like people with nipple clamps on, bondage (specifically around the chest), and other nipple/chest "stimulation" like a penis between the boobs.
Along with all those you need to mix in a good amount of random ones that DON'T contain that (aka plain) and some where those are taken to the extreme (like clamps being pulled off).
The basic idea here is that the pictures are put into a random order/slide show (many ways to do this) and have the person with clamps on view them. I personally set the time between the pictures to 6 seconds, but you can do whatever you want.
Whenever one of the "plain" pictures come up you can do whatever you want so long as the nipples aren't touched. Masturbate, turn on a vibe, or just leave yourself/your slave there wondering whats next while the pain in the nipples slowly builds from the clamps.
Whenever one of the "stimulation" pictures come up, the clamps get pulled on so they go tight and tug the nipples up. You can do this by hand, or if you're really in a mood for pain and want to do some DIY you can tie the chain on the clamp to a rope which goes through a pulley on the ceiling to something lightweight you can add weight to. I think you can see where this is going... Every time that kind of picture comes up you add more weight. The constant pressure along with the unknown of when more will be added really just makes it quite lovely.
If you're doing the above by hand I normally hold it for 2-3 pictures total. So it will come up on 1 (when you see it, and ideally you see it early on), then stay up for another 1 or 2 pictures regardless of content. If the content in the next is another one where it would be pulled up, you add 2-3 to the number of pictures to hold them up. EX pic 1 is stimulation, the nipples get pulled. Pic 2 is also stimulation, the nipples stay up. Pic 3 is normal, but the nipples stay up because of the counter from pic 2. Pic 4 is Stimulation, so the nipples still stay up, and would only go down if 5 and 6 were normal.
For even more fun, normally if I do it by hand I say that any kind of stimulation is stopped while the nipples are in the air. So it's just pure nipple pain with no pleasure. Then they may get some pleasure only to have it stop suddenly and go back to pain. The whole randomness and not knowing whats next just makes it so sweet. Of course, they can't cum either....
If you remember I said there was one more type of picture in the rotation... an "extreme stimulation" like clamps being pulled off. I personally also include nipples being sucked on for extra fun in mine. You may be able to guess where this is going. When one of those come up, the clamps come off... by PULLING. Trust me when I say this is PAINFUL, especially if they have been on some time and have sort of dug into the nipple. Clover Clamps get tighter when you pull them too, so it's doubly fun!
If you're doing it with the weight method you can just add a bunch of weight all at once (4-5x or more if you want) for a nice sudden jerk.
As you probably know, once the clamps are off the nipples are more sensitive... so if I'm really in a torturing mood, I just put the clamps right back on... in the same spot! If done right it is also SUPER PAINFUL, but the squeals and squirming can be oh so lovely. For added fun, make it happen over 1-2 pictures (so like within 12 seconds) or have them do it themselves and if they don't get them back on in a set time they have to have them pulled off AGAIN.
If I'm feeling nice sometimes I'll say they can once the clamps have been pulled off once... other times... Well sometimes I leave them in this kind of situation for like an hour with no cumming. The reactions are... interesting to say the least.
Obviously you can modify all this to suit your needs, but the basic premise is a recipe for a lot of nipple pain with enough unknown elements (will I have to pull these clamps off in the next picture?) to add a dash of mindgames on top. For me, you put those two together, and you have a pretty good torture.