< better. Plywood is probably not the best shelving material; I don't
< know much about this stuff, but wouldn't solid wood be stronger?
No. Plywood is laminated wood veneers and has a strength that exceeds
solid boards of the same dimension. It also has the advantage of oriented
grain for each layer and available with finished surfaces. A cheaper
material is OSB, oriented strandboard the high strength upper class cousin
of flake board.
The idea of glued up (laminated) woods is quite old and has always been
used where strength is a primary concern. It can be used to get grain
and layers that have differing color as well.
Very strong shelves can be made up using 1x3 stock and plywood combined
with 2x4 or 2x6 uprights. The problem is good quality wood has gotten
expensive.
Allison