This is a mitered and splined open box of made of one of the light colored African Mahogany species. The typical way to make a box like this would be to cut a square and then wrap it with the mitered sides. I used a Lion miter trimmer to get perfect miters, made a four sided box and then worked the square part until it was a slip fit, it is just glued in place.
The interchange between hole saws and arbors across brands is pretty sloppy. I had to make a brass shim for the hole saw to get it to run smoothly. It's a six inch diameter saw being used in a drill press, which is still pretty scary since it can ruin the work and cutting the hole is almost the last step.