Thanks, glad I could be of help. I make a 4' tall version of both cages, which can be made with 1 4' x 8' piece of melamine cut up. One piece of wood costs ~ $30, so its a cheap rack to make, not including heat tape.
You COULD wire the heat tape separately for each shelf, but you would spend more money on cords and clip sets then you would for the extra couple of feet to zig zag it. Also, if you are inexperienced with wiring heat tape, the more individual pieces you have to wire, the more pieces you have an opportunity to mess up
The wood I get is technically 49" by 97" which is where I get the 24.5" wide shelves. that is the first and most important cut, to cut it down the middle long ways. 1 1/2 you will cut into shelf pieces at every 12" [or 16" for the bigger rack] and then the other 1/2 you will cut into have short ways, [so you have 2 pieces that are 24.5 X ~ 48" [it doesnt matter if the side pieces get the extra inch, how wide the shelves are (24.5") is the most important part, as the shelves wont line up if they are different widths, if its 12" or 12.5" or 13" long, it doesnt really matter] Then cut one piece every 8" [for the small rack] or in half [for the larger version] to make your 4' long side pieces, and cut up the other ~ 2' x ~ 4' piece into more shelf pieces.
Here is a quick drawing of what I am talking about. The vertical cut is #1 and most important.
