I got thinking about the problem of attaching the tailpiece. I've used “hook” tailpieces in the past, but they weren't all that great in some ways. The nylon 'cello tail guts are pretty highly stressed with guitar strings, so that was an incentive to do something different.    As long as I was looking back for inspiration, I turned to the old viola da gamba. They used a post dovetailed into the tail block that stuck up from the top with notches in the back side. A square hole in the tailpiece went over the post and the tailpiece caught in one of the notches. This allowed for some adjustment of the downbearing force to find what sounded best for a given string set. I updated it by making a ball joint out of ebony. The post goes into a hole in the tail bock, and has a screw projecting from the bottom. There's a barrel nut in the bottom of the post hole that the screw threads into to provide some height adjustment.