I made Moushey at an anthropomorphic taxidermy class at The Observatory, a truly wonderful and truly bizarre gallery space and library in Brooklyn. Making sure he was rightly proportioned and perfectly stitched took me a while, and I ran out of time to build him a kick ass diorama. Though, he seems content with just his wooden boat and his sweater.
In case you were wondering, I did not pick him up off the street and cut him open. The mice in the class came from a herpetology supply company. They were frozen mice intended as snake food. We used Borax to preserve his skin, and his insides were replaced with clay, pillow stuffing and armature wire.