I dimpled the aileron skins this evening. Kerin helped hold the skins open so I didn't whack them with the hammer when dimpling the aftmost holes.

After the dimpling was complete, I riveted on all 32 stiffeners.

I dunno if I've ever shown this before, but this little brass gizmo is what I use for back riveting. I made it at work (with some help from one of the machinists). It works great for holding the gun perpendicular to the skin and also has flats to push down on to really clamp the two pieces together.

It's a nice tight fit on the shank of the back riveting set. If you have access to a machine shop and can make one of these, I'd highly recommend it.