This is really, really easy to do. (Note: you may be able to use this technique to grow other stuff in the form of a square ( actually in the form of a cube) and apply the general idea to other shapes.)
Step 1: Materials and tools
You need 6, 8" square, 3/8" thick (or thicker) sheets of polycarbonate plastic. (Lexan)
You will need 4 gate hinges and 2 hinged clasps with flat head machine screws and hex nuts plus at least 8 or more 1" to 1-1/2" long, thin wood screws and possibly a 36" length of angle iron or aluminum angle (cut to 8" lengths to yield four pieces) if you have thinner polycarbonate, a power drill and hole saw, and a hand saw or power saw such as a jig saw.