Actually Fossil it's not a sleeve but rather an aluminum billet turned down to 3/8" in the center with a 1/2" stop on each end then turned down to 1/4" and threaded for the thumbnuts. Still light as a feather but has a more massive look to it! I've been looking at some Brass 3/8" threaded nipples for light fixtures that would give more adjustment than mine and be stronger than the 1/4" threaded rod. Also slotting the bottom plate to allow for different hole placement on different cameras. Might even look better than the one I made here and be more useful over a wider range of cameras. Looking into it today on the way to work. Thank goodness for A Lowes right next to the Plant I work in! LOL
PS check here and look at photo no. 2 and you'll see how the shaft was made.