I have some of the inexpensive 12x12x18 pvc/acrylic terrariums to house crested geckos and gargoyle geckos for grow out tanks before they reach full size. One of the issues that I have with the tanks, are the slots on the sides and back, which let the tank dry out too fast in a day. So I've come up with a solution that essentially hangs off of the top lip and extends down over the slots on the side to prevent moisture loss. You can set it up to partially or completely block the slots.