Rally, I had looked at pages about that years ago for another project and made a test one out of thick card, but I never thought to look up how to make a round one. Doesn't look that difficult.
I was looking at one of these focusers because my Feathertouch on my newt only has 20mm of travel, but the focal distance of my Wynne Reducer and the MPCC are so different I have to move the primary in the tube depending on which I want to use. The low profile and lack of drawtube make the Clement ideal
Trevor, I could probably use a square bellows, but a round one would be preferable. I have a Pentax bellows, but I can't bring myself to destroy such a nice piece of engineering.