After following this thread for a while and being completely baffled by the circle/hexagon thing, I then had a look at Neale`s fusion drawing, and decided to try cutting a few of these dovetails out. Although I have fusion 360, I still find it easier to work in solidworks so, I downloaded Neale`s fusion 3D drawing and exported it as a iges file. Then in solidworks I opened it up, seperated a single tile from the three, and saved it. After opening it back up as a single file I then shrunk it down to a maximum outer diameter of 48mm, (the width of the piece of scrap chopping board I had lying around was 50mm) and saved it as a dxf. I am now about to go out to the mill and try cutting a few out

If this works, I will take a couple of pics to let you see the results. Just to add, I cannot take any credit at all as I am using both Neale`s drawings, and Peters original input for this experiment. So, big thanks to you both as I think it is a very nice looking and unusual joint !