D. McDaniels wrote:
Hi All,

I need to make several "door" panels for access ports to the attic.
Basically, I need a 1x4 routed frame with a plywood insert.

What's the best fasteners/method to join boards with a 45 degree miter? I
can't afford a biscuit joiner for this tiny amount of work.

Sure appreciate any suggestions.

why not just glue (with a few brads until the glue dries) the 1x4s to
3/4 (23/32) plywood. The plywood will be on the attic side so edging
isn't necessary. or:
half lap miter
spline the miter joint

The way mine are done is the casing is nailed to the framing of the
port overhanging the hole by about 1/2 inch all the way around. The
plywood then just sits on the overhang. To get up there you just push
the plywood up into the attic and out of the way.