An unusual frame.

Actually, not that unusual , though this style, where the corner escutcheon is carved is unusual. I did quite a few of these early in my career, in mahogany and black walnut, though stopped pushing them as the labor intensity tended to make it hard to make a profit. I'm doing a reproduction of a damaged existing frame, with carved, water gilt and burnished corner escutcheons, over stained and finished basswood. Basswood, though usually gessoed, then finished, actually is an attractive wood in itself. MOMA, NYC, has a few examples of stained and finished basswood frames.
Photo above, I'm using an oscillating saw to rough out the shape for the corners.
A corner before gessoing. After roughing out, small carvers rasps were used to refine the shapes.

Another photo before gessoing.

The corners masked off, and the first few coats of gesso applied. Normally I spray gesso, but in this case, all of the coats will be brushed. The first coat was scrubbed in with a toothbrush until almost dry, to eliminate pinholes.