This project converts a xylophone* into a MIDI instrument, but not just any MIDI instrument: a Bluetooth Low Energy (BLE) MIDI instrument. This means that it can be setup within range of a Bluetooth connection and receive MIDI data without being tied down with a bunch of cables (besides power of course).
30 solenoids sit comfortably over the xylophone keys, waiting to strike up melodies and chords either live with a MIDI keyboard or playing along with MIDI data from a digital audio workstation (DAW). It has a lot of potential as either a live instrument or for some extra fun in the studio.
*Yes, technically this is a bell kit, or glockenspiel, and not a xylophone. However, most people will recognize instruments in the mallet family colloquially as xylophones. Xylophone is also comparatively easier to say and more commonly heard than glockenspiel or bell kit.
The model instrument used for this project is fairly common in the United States, as it is often distributed to students in school who begin taking percussion lessons in music programs. You can find the identical model by searching for "Ludwig Educational Bell Kit". There's quite a few available new and used on Ebay, Amazon, Reverb, Guitar Center or perhaps your cousin's attic.
Of course, you can also modify the mounting system to fit your chosen mallet instrument, or any other instrument. As long as it has metal bars it will sound nicely with the solenoids. Any other material bar should have some sort of dampener attached to the solenoid since they could damage softer materials, such as wood.