Originally Posted by Steve C
I think the advantage of it is that it self adjusts to fit the inside of the molded skins when you clamp the molds together. A feature lost on a foam core wing.
You can achieve almost the same with a CF hose with a flexible tube inside. Not a wave, but a trapeze profile. Used a CF hose drenched in epoxy pulled over a straw (Mac Donalds type) to fix a TE spar once. Cures in perfect shape.