I was just sussing materials the for one today found your thread. I had to jump in and say hi.
I'm going to make a frame from plate and glue it too.
I've found euro style hinges and the compression locking latches
but I can't figure out what the inserts for the hinge bolts on the perspex are called.
I've found rubber well nuts but they are not sealed.

I like your idea of the thumb screws I wonder if I could find a black plastic finishing cap?
I'll l keep a eye on how you go