The quilt frames that we used for quilting were made from wood but had some type of fabric wrapped around the wood in which you pinned the bottom of your quilt on. It wasn't in one piece connected but held together by clamps on all four corners.
To put the quilt on the frame, you find the middle of the quilt backing and the center of the frame, then pin all the way across, The side boards are lined up along the end of the quilt and corners are clamped. Repeat on the other end. I understand that is the same process with long arm quilting but with less work getting the quilt set up. No side pinning except with some kind of pinchers.