Guitarists, Meet the FretPen, Your New Pocket-Sized Axe
There's plenty of travel guitars around to practice with, but no usable pocket-sized guitar has ever been made — until the FretPen. Literally the size of a Sharpie, the FretPen harnesses the power of your smartphone to make up for the fact that it only has one string.
The left hand of the FretPen functions similarly to a standard fretboard, and has spacing mirroring the 9th to 12th fret area on a guitar neck. However, since there's only one string, the creator cleverly made a small keypad for your right hand that changes the string the FretPen simulates, making it possible to play scales.
Instead of using pickups or vibration sensors, the FretPen uses touch sensors to see where your fingers are fretting the string. It then communicates the position to your phone via Bluetooth Low Energy, and the FretPen app makes the sound.
The app has a variety of different tones, sounds, and chords — all customizable with effects — and can also help teach you guitar fundamentals that are completely transferrable when you grab the real thing.
Oh, and "FretPen" isn't just a name. It actually works as a pen too.