Working on joints etc atm. I'm leaning towards foam shear webs in the H.S. I could use Coro ones, but my joining options other than rivets are limited to well below the Coro strength. This isn't a problem for air loads, but hidden hangar rash damage worries me. Divinycell H45 has the same specific strength, specific modulus and yield strain as Coro, so that's one option, if a bit pricey. I'm trying to find values for XPS but not getting far there. It's also hard finding a supplier for the denser grades of XPS. If you only want one sheet, you need to find someone who stocks it. If anyone has some scraps, I'll happily pay postage so I can test them. I have scraps of the low grade dow, 25psi, I think. One of the local big boxes has pink stuff and the other the green stuff I forget the name of. I am lacking in the higher grades. I suspect that the yield strain is going to be a poor match.