This is how I set up one of my projects...
I used Aluminum "U" channel and some foam weather stripping. (The peel and stick stuff)
-Drill some mounting holes in the U channel.
-Paint or tape the top of the U channel black.
(Black Electrical tape is the easiest and it actually looks really good)
-Stick the insulation on both sides, inside the U channel.
-Screw into place with some flat screws
Get the foam a little less narrow than the U channel,
so it doesn't stick out when compressed.
Also, Be careful cutting your plexi and bezel,
leave clearance for the screws.