top for c&c cage

I just finished making my first c&c cage and need something for the top. Normally I would leave it open but I have a cat and don't want her getting into it. I do have extra grids and bought pvc pipe to support the grids in the middle. Would the pvc pipe harm the piggies? Is there another way I could make a top? Eventually I'd like to add a balcony but would need to keep the cat from getting to the piggies there to.

Thanks

[yataebo]

You could use the closet organizers that you can buy at Lowes, home depot or walmart.
Do you have photos of your cage?

[DaCourt]

The top to the bottom of the cage is a organizer shelf. The balcony has a door also. The middle grid is only attached with zip ties. The coroplast is cut on either side to allow for easier cleaning.