Covers lid to a C&C

My friend has two guinea pigs in a 2x4 C&C cage. She is now moving the cage to her bedroom. She needs to make a lid for it because she has a dog that will probually try to get the piggies. When she made the cage she bought a ton of grids like this: (broken link removed)
Is there a way she could make a lid out of theese? Pictures would help a lot so I could send them to her.