Keyer-in-a-mouse

I use the K1EL K10+ chip as a morse trainer. The chip has more features built-in than I'll ever get use for.

The keyer is built into an old three button mouse. The center button is the command key and the two others are the paddles. The keyer mouse is completely self-contained: It has a 3 Volt battery, and a piezo speaker located under the mouse in the hole where the mouse ball used to be.

However, normally I connect a paddle and often also a set of headphones.