Looks really nice!

If you wanted to enclose the whole side you could have used MFD board. It comes in 4' X 8' sheets and costs slightly over $20.00 per sheet. All you need to do is paint it to seal it up. Since the snakes never contact the sides all you need to worry about is sealing it so moisture does not affect it. You can also use it to close up the back solid if you wanted too. Then you just use the laminate shelving for the shelves!