I built a divided 3 x 2 x 2 plywood enclosure for my snake. I used 1/2" aluminum c- channels to hold the divider and glass door. Rather than using pond shield, I suggest using a cement mixing tub. I love this tub so much that I basically built the enclosure around it. Here a link to a thread where there is more on the specs of my build: https://ball-pythons.net/forums/show...-for-Antaresia. And here are some pics:
A couple more suggestions. Coat the plywood in poly. This will help prevent warping. But drill your holes first. Once the poly hardens, it will be a lot harder. Use low voc poly, but even so expect it to take a while to finish off-gassing. Update us as you progress and I'm sure I'll have some more suggestions. Good luck.