Presuming you are going to make transparent sides, what do you envision making them from -- glass, acrylic (Plexiglas), polycarbonate (Lexan), or something else?

How water resistant does it need to be (thinking of spilled water and urine)?

If you don't know, you should browse the web site below. I stop in there regularly when I'm traveling I-75.

Here is a link that might be useful: US Plastic

The front would be transparent but the rest of the cage would be wood. If there is too much glass then the lizard is constantly engaging in a stand-off with the lizard in the reflection.

If you don't have access to many tools (e.g., table saw, router, etc., I suggest you go with plywood. If you have a circular saw or want to cut by hand, or have a friend with a table saw that owes you a favor, you can buy a sheet or half-sheet. If you don't, the big box stores normally have a bin of half, quarter, and eighth sheets. I'd go with at least 5/8" thick. BCX would work if you want to go inexpensive; poplar if you want paint-grade. Baltic birch would be up-scale.

You can simply butt and nail or screw the edges together and add a glue bock of 1x1 or some quarter-round molding if you want. On the front, add two moldings separated by the thickness of your "transparent panel," glue and nail them in place on both sides and bottom. Then slide your panel in from the top.

Paint or varnish the outside wood. Leave the inside unfinished or a light coat of shellac (Bullseye Aerosol would work). Or if you want, paint a scene inside to resemble desert, rain forest, or wherever these things live.

Add a screen , hardware cloth, or plywood top to your liking.

That's what I'd do.

that is helpful. thanks.