John,
Thank you for your comprehensive comments, and I agree with you on the design aspects. I shall sit with a sketchbook and see what can be done if I ever decide to make another one, or even a small production run.
However it did not that long to make. The clamp was drilled and tapped as a square then drilled through with a forstner bit that would take my C Jaws, then faced off, edge rounded, reversed and faced again. It was based on the thickness of the board I had, which is why it might look a bit heavy.
The Pin store and Pin cushion did take a little longer as I re-made them twice, while working out the best way to hold them while turning them, Again a forstner bit proved it's worth in creating the pin store area and recess for the cushion itself. Both of which then became the jaw recess.
The threading was done with a 12mm Tap & Die as my thread chasing is still not good enough for something like this and there was no room to get into the hole in the C Clamp with it anyway. The thumb screw was turned round and rasped to a wasted shape and abraded smooth before being glued onto the boxwood thread.
As for a price, is it Treen? Is there a definition of how long something as to be around before it can be called Treen, yes there is for Vintage (50 years approx) and Antique (100 years approx), but Treen I don't know. As long as I don't try to sell it as Antique or similar but as a decorative item, with a possible use in sewing I think I'll be happy. It can be Treen to a collector in a 100 years from now.