I traded my homebuilt TMB130/6 straight across to Markus Ludes at APM for a TMB152/7.9 lens. These tube assemblies were a "fully threaded" design with no fasteners holding them together. This choice was inspired by an Astro-Physics 130 f/6 EDFS I owned previously, the most beautiful OTA I'd ever seen. This scope was made from raw aluminum tubes and billets. Like the TMB130/6 project, all machining was done by Richard Plasencia (DIX Machining) in Cedar Rapids, Iowa. I did the polishing of the bright aluminum parts using the 3M aluminum polishing kit designed for lowering the friction on airplane wing leading edges. Finished up with 3M Marine Aluminum Polish which left a bright surface which did not corrode or cloud.