Construction method

The breath mouse is made on the principles in this development sketch.

I took a belt from a charity shop, and braces too. The belt is black, and the braces blue.

I chopped the belt in two, six inches from the buckle. The two half-belts are fixed together with a 3 inch piece of elastic (made from two 3 inch pieces of the braces stapled together). The buckle end is firmly attached to an optical mouse. (The optical mouse happened to be a quill mouse kindly donated by www.quillmouse.com, but any optical mouse would probably work.) The belt attached to the other end of the elastic moves relative to the optical mouse, and these motions are turned into screen-mouse motions by the optical mouse's magic. I mounted the mouse on a piece of wood and ran the moving end of the belt over a metal bearing to try to reduce friction.