Coffin shaped shelves are surprisingly common, but most are designed for only one wall. I decided to take a slightly different route when I made this small coffin inspired corner shelf. This shelf was made to match the decor of my niece's house.
The top, bottom, and shelves are curved with a radius to match the width of the sides at that location. The exposed edges of those parts are beveled to match the slope of the sides. The upper shelf is set just under the outside corner of the walls. There is no fancy joinery here. The shelves are just glued in place with butt joints. Countersunk screws driven from the back help secure the two inner shelves, while 23-gauge pin nails helped hold the top and bottom in place while the glue dried.
There is a 1/8" round over on all exposed edges. The back corner has a 1/4" round over to help account for any imperfections in the wall where it is mounted.
The both sides have a Z-clip for mounting, although due to the relatively small size, one clip would likely have been enough. I included two additional Z-clips for mounting to a wall.
The finish is a black gel stain topped with a semi-gloss polyurethane.