Somebody warn Fritz about these images. I fear that they could trigger his CMD.Early in the Facetmobile program a reduced scale airframe was built from PVC pipe. The fishmouthing on the tubes was done on a CNC router table that had a rotary axis added. One could also do fishmouthing with a spindle sander that can be bought fairly reasonably or one can make one using a drill press and a sandpaper wrapped dowel. The corners on this mockup were held together with riveted gusset plates. One could also glue them with pvc cement, but you have to hold the joint together with duct tape while the glue dries.