A friend found this "Music Maker" lap harp in the free-box of our neighborhood and gifted it to me. I automated it with solenoids and an Arduino Uno. The light grey parts were 3D printed on a Prusa MK3s and designed in Autodesk's Fusion 360. The plywood stand was laser cut on a Boss laser cutter. On a laptop, LMMS (a free digital audio workstation app) is playing midi files which are downloaded from the internet. A program called loopMIDI creates a virtual patch on the computer so the midi signals from LMMS can be sent to Hairless MIDI, another app that creates a USB serial bridge to the connected Arduino Uno. The Uno has a simple program running, built with the MIDIUSB library, that waits for a midi 'note on' signal, then plays that note, if possible. It does this by digitally writing one of the Unos GPIO pins LOW, which is connected to a relay board. The relays control a separate high amp, 5V power supply for the solenoids.