Well, today, my mom brought home this large, 3-story doll house initially intended to be for my baby sister, but I asked for it as an alternative to buying a cage for some mice I plan to get...Is this alright if I ventilate the house to make sure the aromas don't get all cooped up, and if there is a sufficient air supply?
I'd suggest buying a cage. Mice are smart and will eventually chew through the doll house and you'll need to clean it everyday super well in every nook and crany of it, you'll need to block off all windows/ doors/ and enter/ exit ways to the doll house, etc. So I suggest just buying a small metal cage or aquarium. It may not be cheaper but it'll be easier.
My; dogs: Blizzard and Max. cats: Frosty, Snickers, Crystal, Felix (black cat in pic), Sinder, Vince, Binx, Rei (tiny cat in pic). Birds: Ash (cockateil) Fitch & Sheila (Zebra finches)