"Puckdropper" wrote:

The miters are actually there more for the aesthetics than strength.
I
was just going to use standard butt joints on inner frame, but might
try
box joints if I have enough material.

Personally I like the aesthetics of a good box joint over a miter.

Even with a good sled, miters are a PITA to get and keep aligned
without biscuits, IMHO, but to each his own.

BTW, a half lap for the inner frame might be nice.

Have fun.

Lew