You're right about the cork, more holes to fill. I usually use thin coats of flat white and sand them between coats to fill. I guess I just never got away from the cork. I do use balsa pretty much equally. I like to get the 3/8 X 3/8 and 1/2 X 1/2 sticks. I can usually get 2 dozen bodies per foot.
I haven't had much trouble with the cork letting loose. The wicking properties of zap-a-gap make alot of difference. But definitely not as durable as balsa.
Does anyone have a good process for cutting foam popper heads. I do have a set of punches and the darn things are tough on your hands! I'm curious as to how everyone else does it! Thanks