The SuperClamp System
This is one of those products that you buy for one need, and find it has a hundred other uses. The Manfrotto SuperClamp (Avenger also makes a version) is more than just a super robust clamp that will take a MagicArms. The SuperClamp is a whole system of camera studs and arms that allow you to clamp almost anything to a pole or flat edge up to 3 inches thick.
Because the clamp is cam locked, when you tighten it, it stays tight. It supports far more weight than you would expect.
As you can see from the picture there are almost dozens of accessories making limitless combinations.