Got a 3D printer to hand and don't have a watch? Why not print one? David Ng is a mechanical engineer who did just that. His rather large wristwatch displays the current time using normal 7 segment LED displays. David has added a 3-axis sensor so that the time is only lit up when the wrist is raised up as it would when reading a standard watch. Bring your arm back down and the lights turn off.

The electronics are based around an Arduino board to drive the display and sensors, and a real time clock to make sure the watch is accurate. The power is supplied from a mini portable USB power bank, and everything is fitted into a one piece wrist band.

David's wife had an idea during the development, that the watch should incorporate an alcohol sensor. You could imagine people, who have gone to the pub for a pint after work, getting side-tracked and staying for another, and having to check their watch for the time. As they do they breath on the watch, and the sensor sounds the alarm if they are over the limit to drive... TAXI!

It's a brilliant little idea, but it is quite a cumbersome design. It could made made a lot smaller by using a little LED screen, or smaller 7 segment displays, and using smaller batteries and an SMD ATMega chip; but it wasn't made for commercial release - it was made for fun of it!