[Photon46]

If you order from an art supply dealer, you can get much heavier duty stretchers the the thin ones you find in your average arts & craft store.

https://www.dickblick.com/categories/stretcherstrips/

[artur9]

I actually got mine from a B&M Blicks!

[MarvinTheMartian]

www.primacoustic.com/broadway-panels/

Have an interesting twist on the standard wood frame construction.
They reinforce the OC703 edges by applying a thick coat of glue.
Thinking 3 perimeter coats of epoxy applied with a roller. Soak the corners?
I'm a woodworker first so I have never tried this technique.

Also like their idea of cheese cloth? / 3M 77 spray adhesive containment cover.

Shawn