Bleh... I can't get my scanner to work, so I can't share the drawing of my plan.
Anyways, here are the dimensions I used:
Vertical sides (x2) = 29"
Shelves (x4) = 28"
Top (x1) = 32"
Space between shelves (for tubs) = 6.5"
I used 15-3/4" wide melamine boards (they were labeled as 16"). I bought two (2) 8-ft boards and one (1) 4-ft board, which the hardware store cut to my measurements for me.
The boards are 3/4" thick. If you make a rack like this, BE SURE TO TAKE THE THICKNESS OF THE BOARDS INTO ACCOUNT!! (I almost didn't. LOL!)
I built from the bottom up, using a carpenters square to be sure I was making right angles. When I had the bottom shelf attached to both of the vertical sides, I measured, "test fit", and marked the other three 28" shelves into their places. I used screws straight through the vertical sides into the shelves (later I painted the screw heads with whiteout and covered them with round sticker labels from an office store). For the top, I put the screws through the top into the vertical sides... Not the prettiest solution, but the 20L viv sitting up there covers those holes very well.
To finish the side edges of the rack top, I used some iron-on edging tape. I found it near the melamine boards while I was buying supplies.
For heat, I'm actually using 11x11" Ultratherm UTHs from Reptile Basics. (
http://www.reptilebasics.com/ultratherm-heat_pads/) It's what I happened to have already, and I really like them. For the 15qt tubs, I just put one exactly in the center of each shelf near the back, so the tubs each have a corner on the UTH. I have the UTHs taped down to the shelves with aluminum tape.
If (when) I add more snakes to the bottom two shelves, I will probably switch to Flexwatt. For now, though, this setup is working very well.
Hope that helps! Please feel free to keep asking questions. I may have forgotten to mention something.
ETA:
Thank you all for the compliments!
