Are these locker shelves safe?

[GuineaPigPerson]

I am using one of these (Folded down and grid covered in fleece) as a ramp but when my C&C cage comes in I really want to stand it up and drape fleece or a towel over it and cut it to make curtains (I will also put a little mattress made of fleece or something under it). I was wondering if these are safe for them to gnaw on?

It looks like this, I have a few different colors:
http://www.organization-store.com/images/tallshelf.jpg
http://www.goteeniebopper.com/images...cker-shelf.jpg
http://ecx.images-amazon.com/images/...500_AA300_.jpg

[GuineaPigPerson]

Anyone...?

[PeeweesPiggyPalace]

Do you have a Photo..??
Oops.. Photo just didn't load.. Does it have the plastic coating?

[doganddisc]

I would assume it depends on what they're made out of.

[GuineaPigPerson]

They feel just like grids, I took off the part that allows it to stand and used zip ties to make a hay rack because the pigs are fighting over the one I got from Guinea Pig Zone.