Keith Baxter made a hand held MIDI keyboard called The Kyub. This device using capacitive sensing and has an internal accelerometer for controlling the volume.
This video from their Kickstarter campaign gives a good overview and explanation of how the Kyub works.
This is a pretty cool video demoing the Kyub configured as a set of drum pads.
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.
Marcus Herbert took an inexpensive ukulele, cut the strings off, designed some circuits, and turned it into a fully functioning laser ukulele that sounds great.
Some of the features include:
Custom tuning mode allows 128 notes as per the MIDI standard (12 notes [C, C#, D, D#, E, F, F#, G, G#, A, A#, B] across 11 octaves for C-G and 10 octaves for G#-B)
Full soprano ukulele fretboard (12 frets)
Four lasers as strings
Virtual capo can be placed along any of the 12 frets
Although this is in the shape of a ukulele, the computer software determines the final sound, so the physical instrument could end up sounding like whatever instrument you desire
Note velocity can be customized from 0 to 127 and is displayed on the LCD screen
The ENCHANT board is a light and sound controller with an accelerometer and gyroscope. It’s compact size makes it ideal for props, like light sabers, and wearables.
This video shows the light saber in action.
The rewards in their Kickstarter campaign include levels from an ENCHANT board, an ENCHANT wearable skirt, and multiple light sabers.
NeuroBytes are hands-on electronic neuron simulators that allow individuals to learn about the brain while physically building their own neural circuits, synapse by synapse.
The project came about when he was having difficulty getting an expensive input board to work in a haunted house attraction. When he discovered that the iCade keyboard commands worked over a USB connection, he figured he could use an Arduio board and hood the USB side to an iPad and create his own interface. With a bit of research he got his project up and running.
Be sure to check out his forum post for details on how the project came about. The code for the project is available on GitHub.