Bracing & damping large plastic waveguides?

https://jblpro.com/en-US/products/md2

I have these waveguides with no box. If I never had to move them, I would build a similar box and brace/damp accordingly.

I would like to keep them free-standing, but increase the stiffness with minimal weight added. Maybe damp if the resonances are too noticeable.

I was thinking of gluing 1" wood strips spaced a few inches apart, then spraying some kind of thin rubberized coating. Anyone try something like this on similar devices?

Thank you for any input.