I just installed my new attic hatch made from Maple :)
It’s built with a 3.5”x 3/4” frame to fit into the hatch hole. I added a 1” runner on the bottom that has a 3/32” rabbit cut along the side facing the frame that accepts snugly a length of magnetic weather strip that seals to a metal trim around the outer edge of the hatch door.
The door is 3/4” plywood to fit the frame square and has foam insulation on top of it.
I finished it with some Antique Oil based finish ( I know I won’t be able to see it, but seen it as a good opportunity to test oil finishes since I’ve never used them before
Here is a side view of the accepting track for the weather strip.