Is there solid wood behind the drywall? A 'piano' hinge at the outside edge of the panel you made would work fine as long as there is something solid for it to attach to behind the drywall. Otherwise make a smaller door that fits inside the opening so the piano hinge can attach to the existing jamb

No wood behind that drywall where the outside edge of panel lays. So besides a hinge are there some kind of clamps that might work?

No hinges; make it removeable. Fine for as much use as it'll probably get.

Honestly I would remake it smaller so it fits IN the opening so it can be hinged- it looks fairly awkward to carry up a ladder. You would need several magnets or a latch as well as two handles to carry it by if you want it to be removable.

Maybe I can just add some wood blocking behind the drywall for piano hinge. Then I would need to fix my almost finished drywall 🤦‍♀️ I can’t make it smaller without redoing the door, it would throw off the scale of trim. What kind of latch will work?

Have you tried carrying it up a ladder? Looks heavy and awkward

I have and it’s manageable even for an old lady like me. Like you said it won’t be getting that much use for getting into. A handle would make it even easier.

you could do face mount cabinet hinges on one side, and a magnet latch. it'll look fine.

I'd be worried that if you made it entirely removable, with hidden latches on the inside, it could come undone and fall on somebody.

I don’t think those hinges would be strong enough. Good point about falling though.

if you're scared about strength issues, bring your door into a cabinet store and ask them for help choosing the right hinges.

I'm sure hinges like the example I posted would be strong enough. here are the exact same ones used our other closet doors. one of the upper doors is 17x51". each hinge is 2.5" and made of brass. trust me, they are strong.

IloveMod, they do look like they would be strong enough, thanks for the pic.