I have built a CW keyer. I can not copy CW very well but the main use for this one is for a beacon. I also added the 'paddles' to the circuit, but that is just for testing it out and not so practical to use. I searched around a bit to try to find a suitable software. I wanted it to be open source software and use an Atmel MCU. So I found http://lategahn.2log.de/index.php?yack-yet-another-cw-keyer . It is basically just a few components, Attiny45, voltage regulator and a piezo buzzer . Here is a video:
The user interface is via CW and I have not yet programmed it for beacon use. When I put it that service I can just move the chip over. We will see when that happens. So many interesting projects going on at the same time. This is a fun hobby!