here are some pics showing how I set up a mouse cage. I just use those plastic toats that you buy at the store. I usually either cut a hole in the lid and replace it with wire or create an entirely wire lid.
I fill the bottom of the toat with a cup to a cup and a half of pelletized bedding from TSC.
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Then I add a layer off straw. This pic is blurry.
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I also put some pelletized bedding in a little litter box in the corner. It's really just a small coffee can turned sideways in the corner.
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Then the food and water is water is added so that I can finally add the mice. (There's more than one mouse in there. They just enjoy making nests under the straw.)
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