I'm wanting to make a fairly large (for me) mosaic for an outdoor space. To keep costs down I'm planning on fixing two posts in the ground with concrete and then using a large 8'x3' piece of pressure treated plywood for the mosaic support which would be affixed between the two posts.
Is this feasible? Is there anything which would be economical which would be a better substitute for plywood?
I'm going to do a mosaic based on an abstract painting inspired by my love of Rothko and Seurat.
Here's a photo of what I'm going to recreating with glass.