Love the topic. The best tricep exercise I ever did and it worked wonders for me was dips between two benches (hands on one, feet on the other). You didn't need a belt to help add extra weight as you can just rest plates on your legs (I recommend resting them on your quads so you don't strain you knees).

This way you can easily tweak your form to really target the triceps and to take it further, you can do the dips with the added weight, shake off the weight and do more until failure, THEN just do half dips, only going down half way.

This absolutely kills your triceps and definitely made my arms bigger (currently 18.5 inches).