By attaching the mirror cell directly to the bottom permits the weight to be as low as possible. Since a six-point mirror cell is easier to make than a nine, and because I was curious to try out the prediction, I made a six point mirror cell. The mounting hardware is the same as taught by Bruce Sayre . The beams pivot on stainless steel shoulder bolts. The mirror is then attached to the support pads using silicone caulk.
Adhesives are very good in shear.
What really makes this scope lightweight is the primary. Unfortunately I don't know its figure. The bearing surfaces are the conventional ebony star Formica and Teflon. In this image you can see a close up of the altitude bearings. The outside surface of this lip, one on each bearing, rides against the inside surface of the Teflon pad, and keeps the scope centered in the rocker box.