My guinea pigs have been chewing certain spots of their C&C cage for a while now and I'm starting to get concerned. Is the grid safe to chew? Also, it's not the outer walls that they are chewing (those are completely untouched), it's the inner one.

Ok, that might be a bit confusing. So I have a 2x4 cage and I made a hidey for my guinea pigs using C&C grids (2 that are in opposite corners of the cage). I placed it like a rack, but there's only one, very large entrance. I tried looking for a picture, but I couldn't find one.

Any ideas? Solutions?

Thanks in advance