I currently sues stitch clips to hold my fabric taunt horizontally on my scroll rod frame but I recently saw a different clip on another post. I wonder if anyone knows what they are called or where to buy them. I bought the ones I have at Nordic needle in the US but the ones I saw on a post were much nicer. They have a garter clip on one end and then a fastener that wraps around the side of the scroll frame.
There are things called tarp clamps which would do what you are looking for, but the clamps in the picture look like they are something called Grace Quilt Frame Bunge Clamps. Myself, if I needed something like this, Id go for the tarp clamps since they are a lot cheaper and more readily available. I found both on amazon.