It didn’t take long to cut out the new tailpiece shape with hand saws, but I had a sore shoulder for a week or two afterwards!
Fine shaping did not take long either:
I was aiming for something a bit prettier than the original chunky item, but still with strength in reserve. Maybe eventually I will do a third version that is as thin as on some of the old kontrabasharpor – though they had gut strings rather than modern steel and synthetics.
The string end is now approximately shaped; I now need to get a carriage bolt for attaching the extension before I shape the tail end.