Two local RV-6A builders (Marc Guay and John Lukes) made a neat attachment for a pneumatic rivet squeezer to allow it to be used to dimple large skins.

It was made from a piece of 3/4 inch steel plate about 32 inches long by 20 inches high. It is essentially a very large squeezer yoke, with a 20 inch throat depth.

I clamped it in a Work Mate table (also graciously loaned by John Lukes), and used a piece of 1/4 inch plywood with a 1/2 inch hole (to go around the male dimple die) as a table. This thing does super job! Quick, perfect dimples. Thanks John!

Here is a close-up of the dimple dies and the plywood table.