Iv been using boxes in cages for decades, all shapes and sizes. Yes, it got so bad once that I started buying things (usually edible) because the boxes they came in were wonderfully hamster sized (Syrian).
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Proud mummy of Fluffy
I started off with one hammy...but one is never enough
I didn't have any easter eggs this year, but last year I used the little cardboard "baskets" that came inside the easter egg boxes for my Syrians and they loved them they got chewed aswell and didn't cause a problem
I gave Teddy his box last night. LOVES IT! haha. It's got a print on it that makes it look like a basket, so I tore a corner off and put it upside down in his cage. Looks great and he runs in and out of it all the time