@hilde45 - I was surprised to learn from a good friend and cabinet maker, that balsa is actually a hard wood (by definition).
This is the very first effort making diffusers, and that being cherry wood only. No idea how that would work out, I am surprised that it would degrade though?
I only used balsa wood as a kid, I’d glue wings on a dowel and shape them for lift. Tear apart a golf ball, which was not easy, unravel the rubber band that was under the skin (are they still made that way, I have no idea?) and make a loom from the rubber and use the local park’s slippery slide as a large slingshot to send it up into the sky. Like boomerangs, every now and then losing them in a tree, at least until the next big storm. Other kids would end up with new (to them) toys. Surprisingly light, the balsa planes could withstand a flogging, they fell a long way after being shot up into the air.
** I used the plans I purchased from Acoustic Fields for my QRD17** With a little modifications in the CNC program, the resulting geometry being the same as the plan, just didos are different.