*I have not actually printed this because I don't have a 3D printer yet!*
I'm not sure why I made a mouse wheel... it just sounded fun. I'm pretty sure your mouse will eat it, so it's not very practical, but it was a fun project nonetheless. I am completely new to 3D modeling, so I apologize if it isn't perfect. I tried to break it up so that it wouldn't need much support structure, if any.