Thinking about making one of these!

Try using the small maxi-view corners sold by United. (Part #U3983)

These frames can be easily built using Boxers with the short extenders or most any moulding onto which you can install a "door" moulding.

If you don't care to put hinges and a hasp/latch on the "door", hold it in place using the rare earth magnets and some strategically placed flat head wood screws such as I used on the shadowbox that held the fishing lures.

I'll try to find the link to the thread with that shadowbox for you.

swing frame maks them as well. been using them for years. i have some comic collectors that love them.