This helps guide the filament, adds a surprising amount of rigidity to the otherwise not-so-rigid z-rods, and looks great doing it. It prints fine for me without support material. I stuck my own support on in the form of those circle things that keep the spheres from rolling away before they join the rest. It trims off easy. I included two versions, one uncorrected, and one corrected for the tendency of these printers to squash horizontal holes. Print the clamp_test.stl first to see which one you need. If you need to make some other adjustment, I also included the OpenSCAD file, but I wouldn't look in there if I were you. It's ugly in there...