Dog-Proofing the Litter Box

I was googling around for info on keeping dogs out of the kitty litter a little while ago and ended up at a site that sells covered cat boxes that dogs can't get into. They're sort of expensive, and a little more complicated that what we'd need since Prancis is big enough that he could be foiled by something pretty simple. Here's what I came up with:

It's not to scale, but there's the general idea...a little doorway for the cats and an interior wall to keep Prancis away from the goodies. (The litter box on the inside is a model I found on the web.)

I got the wood cut to size at the wood store and put it together with drywall screws because they are the best.

They wouldn't do curved cuts, so I had to get a jigsaw (racist).

And here it is set up:

The Colonel (and hence Lucy) can get in:

But Prancis cannot:

I still need to sand and paint it. The inside should be glossy white for ease of cleaning. Not sure what we'll do with the outside.