I've done a bit glass molding in the past, but somehow working with balsa is more satisfying to me. I suppose that goes back to my beginnings in modeling when I built with balsa and ambroid. That dates me big time.

Over the years, I have used formed balsa shells with glass/carbon fiber applied to both the inside and outside surfaces. This allows me to work with balsa but achieve many of the advantages of molded construction - strength and rigidity in a shape with compound curvature.

The reason for applying glass/carbon fiber to both sides of a balsa shell is to dramatically increase strength and rigidity (particularly in compression) as compared to either a pure balsa structure or a pure molded glass structure. This is pretty much common knowledge, but it is always a lot of fun to see a relatively flexible piece of balsa become as rigid as plywood.

In the first pic below, a piece of 1/8" x 4" x 14" balsa (10# density) is suspended in a vise with a 3.5# load applied in the middle of one end. The bowing is evident. In the second pic below, the other end of the balsa has been laminated with 1 layer of 2.3 oz glass on one side and 2 layers of 2.3 glass on the opposing side. With the same 3.5# load, there is very little deflection.