Ok, I am not the first to use this design, nor will I be the last. It is a good design and fairly easy to do. So here goes. I am not a carpenter, however, I do have a small history with power tools. So here goes. First you need to determine what size you want. I am making one with the same dimensions as a 20 gallon long fish tank. 30"x12"x12". This is going to be for a fire skink and the lights will not be on the inside of the terrarium. I will be cutting holes in the outside to place the fixtures in. Ok, so lets begin. First you will need some supplies. I am going to use 1/2" MDF. You will also need some 1 1/4" inch wood screws and some wood glue. The screws. The glue.