DoN. Nichols wrote:

But your plywood would be the limiting factor on lifetime. How
long do you need this to work before it is taken down?

Only 2 months life needed.


See whether you can find a local shop which needs to make discs
of aluminum from sheet. You may be able to get them to cut from the
center of the sheets and sell you the "drops" -- squares with round
holes.

Great idea.