As I was going through old photos, I found some pictures of making the shoe shelf.
The frame is made of pieces of particle board that were packaging material for some furniture. I used angle irons to attach the pieces together, because that's the easiest way.
Then I attached the center shelf by gluing strips of wood to the vertical parts for support and then gluing the shelf into those. I glued cardstock to the front edges, so they would be smooth. Usually this is done with strips that are laminated to the edges, but I didn't need anything that durable, just a smooth surface.
Then I used paper napkins and glue varnish to cover the frame all over.
The other shelves are made of cardboard, attached the same way as the center shelf, and then covered with napkins and glue varnish. Finally, I attached some overhead transparencies to the front for keeping most of the dust out. The transparencies are only attached on the top edge, so you lift them up to access the shelves.