Hulk's my favorite superhero(well, tied with Venom) so I would totally get this. Now for some fuggestions:
1. Also a hulk fist cap?
2. One in red
3. I love Hulk like a sentient unformed twin attached to my neck, but his short bus haircut always makes me cringe. If you zoom in a bit you can get his whole face across the cap leaving much less negative space and really capture his rage.
4. ONE IN RED