Above is a tool I made for bucking 3/16 body rivets. I went to the used tool store and bought a dead taiwan air hammer for $3 and bought an old steel workout hand weight (~10 lbs)
I took the front end of the dead air hammer apart and welded it to the knurled weight. It makes a nice hand anvil in which I can interchange rivet sets (available from aircraft tool supply places). I use the hand anvil with my good air hammers to rivet with. This way, one (sometimes) or two people can do the job and have good control of the results.
I like to use the waffle tool in the hand anvil and have someone press it against the rivet, while I air hammer the rivet head with the proper cupped rivet set in the air gun. It may seem a little counter-intuitive that way, but that is the proper way to air rivet and I get better results that way compared to putting the waffle tool in the gun. Both rivet sets are kept in contact with the rivet, and the waffle set and hand weight is used to buck the rivet.