In the toy aisle at places like Toys R US, they make doll sized tents...that should be pretty close to what you want. Frankly, those things are WAY too loud at 3

ETA- two people on another site said Family Dollar. If I remember, I will double check one around here. It does look pretty cool. Loud, but, pretty cool. Beats the two cardboard boxes set up now in the living room..