I picked these up on a whim as I needed a second 'third hand'. They are remarkably simple, and I put them together in two minutes with no tools except my hands. One of the clamps is smooth, and the other has ridges, but they probably will not hold anything very heavy. The clamp stands are held in position by rubber O rings that I bet I can buy for pennies at the local hardware store if these wear out. They are not great looking, but nor are they expensive. They fit a niche and seem to work for me so far. I gather that if you bought more than one set you could add a few clamps to the base (if you needed to).

Found they could use a tad more weight in base. Accomplished this with simple modeling clay.

excellent for light weight projects ... the base bottom could be a little heavier other than that i like it