I wanted a rack for storage of ply sheets ready for placement onto the CNC. The rack was designed to keep the materials off the ground so that they would remain dry. I wanted materials to be stacked near vertically so that materials could be inserted and removed without needing much effort to separate the sheets. The rack also needed to have a high enough support on the front face so that sheets could be pulled forward without causing the rack to overturn. I made the rack from 50×20 RHS, I think the walls are ~3mm thick.
Happy with the result. Happier still that I managed to get a weld down (albeit a bad one) after not having practiced in years. Results below.
Next step: an overhead vacuum crane to load sheets! https://www.instructables.com/id/How-to-make-a-vacuum-powered-plywood-lifter-for-yo/