A complicated lid... ideas appreciated!

I bought an Exo Terra "turtle terrarium" on clearance a couple months ago. I love it. It has a lot of floor space (23"x17") and is a great size if I ever get my leo, Faust, a girlfriend! One drawback: my cat tried to stand on the cardboard I used to support the lights and fell in... I need to make a lid for the tank. Faust is being safely housed in a 20 high for the meantime. It doesn't have to support the cat's weight, but it needs to be a properly-fitting lid. I was hoping to make it acrylic (plexiglass) for the back half, and screen for the front half, with a piano hinge in the center. Does anyone have any suggestions on how to frame out the lid and attach the plexi/screen to the lid? It is a really odd shape, because it angles down in the front half. It also doesn't have a frame around the top rim of the glass.

Here is the tank on Exo Terra's website:
http://exo-terra.com/en/products/turtle_terrarium.php

Thanks to anyone who might have a creative solution to this issue!!!
Faust and I appreciate it greatly!