The ones I've seen are made of a heavy plastic . I do something similar but don't leave the template in the fabric and lay my fabric down on the shelf instead of standing it up. I measure the width of my shelf then decide how many stacks of fabric will fit in that space - on my purchased bookcases I can get three stacks per shelf, so I take the length of shelf, subtract 1.5 or 2 inches to allow for space between the stacks and divide the remainder by three. Thats how wide I cut my template used for folding fabric. (I cut up a damaged cutting mat to use for this purpose.) To fold fabric, I first fold it down to about the size of a fat quarter, then lay the folding template on it and fold the fabric over the template to get the final size. I always plan it so that the final fold is on the short side of the template, or the bottom. Slide the template out and lay the fabric on the shelf with the final fold to the outside. Doing it this way keeps the outside edges smooth so you can easily see the fabric. Also, the stacks tend to lean away from the final fold, so they lean toward the back of the shelf.