Finished riveting the skin to end ribs. Could not access one rivet with anything I had - no bars, squeezer yokes, etc. It was the hole marked 4.5 in the pic. One builder made his own bucking bar from a ground down prybar, but I took the path of least resistance and put in a MK-319-BS blind rivet. The ones below it marked 3.5 were on the inside of the control surface, so that was bucked conventionally - my son with the gun on the top, and me with a bar reaching deep inside. Next, the trailing edge to wrap this up - similar to the rudder trailing edge and just as trickiy, perhaps more so as the wedge piece that fits between the skins is not predrilled.