Eli Fatsi made his own Iron Man-esque shoulder mounted Nerf gun that can be controlled by a Pebble watch.

With this cool project you could be like Iron Man and destroy your enemies by simply touching a controller on your wrist.

The code for the project can be found on GitHub.

Elliot Carter published a tutorial on making a photoresistor-based tachometer.

The project came about when he needed to test the top speed of a stepper motor.  After putting it together the project became an important diagnostic tool for a larger project – not only does it test the top speed of stepper motors but it also works as a tool to verify code.

The tachometer measures rotational speed using only simple light sensor with an op-amp comparator circuit.  While many mechanical engineers might cringe at the thought of an op-amp, Elliot’s team found a tutorial that explained them well.