I haven't seen the thread, but I have an idea about how to do it.

At Home Depot you can get aluminum u-channel. Get one just think enough to have two pieces of plexi-glass (which can also be bought there but cutting it without experience might be hard, so a local place that deals with plastic might be easier, such as Tap-Plastics in my area) by-pass eachother. Most plexi-glass is ~1/8" so a ~1/4" channel would work. Lastly, get a glass display door lock, which you should also be able to find there (This is an example).

To put it in you will need an adhesive that can bond with glass so make sure it says that it will specifically.

I would suggest getting Lexan or Poly-Carbonate over regular plexi-glass because they are scratch resistant and would look nicer/clearer longer.