1) Just because you are getting better at riveting does not mean you should overdrive the rivets.
2) About any piece of metal with weight and a flat surface is a good bucking bar. (big sockets, crow bar ends, my head)
3) Buy lots of clecos
Fitting the skeleton to the skin using the skin as a template.
Truing of the skeleton in the jig with a plumb bob
Dimpling of the skin worked better without the plastic.
Had to be careful not to scratch it with the male dimple
Proud owner of a completed vertical stabilizer.
The first part actually completed