I have made something for my newts that seems to work. You need the aquarium design with the plastic on top having an extrusion inside the tank that serves as sort of a ledge- most newer aquariums have this. Using straight 1/2" x 1" poplar, I made a frame that fits precisely inside the aquarium, and rests on the ridge. I then used 1" x 4" boards plexiglass would also work), and screwed them onto the poplar sticks. This in essence made a wooden cover, that is open in the center. This gives access for feeding and light maintenance, and a flourescent light can be laid over the top. I put additional wood strips under the light, to raise it up for heat dissipation. I also made a small notch in the poplar stick to allow for an airline, which then remains in place when the top is removed.
Essentially, you can access it without removing the lid. Unless you have salamanders that can crawl upside down under the 4" boards, it is escape proof.
