Getting ready to start my doors on the Cubby. The plans call for a hollow door with framing between the walls. Is there any reasons why one could not just use 3/4 inch ply between the inner and outer skins and just cut the hole for the window??? A solid core door if you will. ??
You may (may) get condensation on the door without the insulation in it and it will be alot heavier, but not unreasonably heavy. Also, the door will not be even with the inner sidewalls either and you may have some problems (or difficulties) getting your latch setup on and working they way you want it to.