The Evening Woodworker - This is the simplest plywood storage rack you're gonna find that won't break the bank to use or make you use all of your plywood to store... plywood.
Innovative DIY Wall-mount Lumber Rack For Boards and Sheet Goods – Gadgets and Grain
Plywood Storage Rack Plans • WoodArchivist
Plywood Storage Rack For My Shop | Jays Custom Creations