The stock for the frames is pine which is cross-veneered on the outsides with the same 5/64″ (2mm) thick walnut veneer as the frets and the top is faced with 1/4″ (6.4mm) thick cross-grained walnut blocks. I made the stock up in two lengths; one per frame which virtually guarantees a smooth transition across the mitres.
I glued the frames together and when dry, I sawed diagonally through the mitre sides until the saw barely appeared on the inside of the frames. Veneer splines were glued into these saw cuts to strengthen the butt-jointed mitres.
The frets were glued in place on the frames and supported from behind by small glue blocks. The mitred cross-grain blocks at the top corners of each frame were cut out and replaced by wedge-shaped blocks into which were carved the re-entrant, or ‘baby’s bum’ corners. They are peculiar little corners because conventionally, each set of arcs is not concentric as one would expect (re-entrant corners on table tops of the same period, for example, are concentric).