The aluminium DoveTail is designed and made by William Strijbos. It is really a nice solid piece puzzle and very well machined with excellent fit. Measuring a petite 2in x 1 3/8in x 3/4in, the object of the puzzle is to separate the green convex shaped portion from the polished rectangular block. Mine has the #16 engraved onto the puzzle (the 16th unit that William made???).
Oli's and Jeff's blogs.