I came across some scrap 80/20, so I made a Mendel90 enclosure with it. The interior volume is a 19" cube, which fits well around the Mendel90 without its standard reel holder. My design uses a front door and a top door, which both provide enough access to the usual needs.
I used a standard 12V LED strip lighting to align all interior edges and hooked it right into the 12V power supply. The ends of the 80/20 were tapped for 5/16-18, and the printed components make perfect corners for the enclosure and the doors.
The main length of the 80/20 parts are 19.0" for the exterior, and 15.825" for the doors. The clear panels are .250" thick acrylic; the large size is 19.75" square and the door size is 16.50" square. Each panel size has .30" square cutouts in each corner to not interfere with the printed corner brackets.
The .25" thick panels are thinner than the channels in the 80/20, so I squeezed in small rubber grommets to keep the panels from rattling around.