To handle the actual fabric storage, I wanted a box behind the frame with four or five shelves. I tend to have a lot of fabric that ranges in size from fat quarters to a yard or two, so I was hoping to accommodate that size range. The frame fits a 30" x 40" piece of glass, so I went to the Home Depot and got 1" x 5" (which is actually .75" x 4.5") boards cut to size. Each shelf is 30.5" long, and the two side pieces are 41.5" long.

Step one was to create the frame, which I did using interior construction screws (this is a very, very sturdy unit) because that was what I had on hand. Next I played around with the number of shelves that I actually wanted, and opted for four. In retrospect, if I had considered fabric colors more carefully, I might have gone for five, but oh well. At the point when the decision was being made, it was being made in a pretty arbitrary manner. I attached shelves starting in the middle, and then going to either side.