"MagneTrack" MIDI Instrument

The new iteration, “PipKey”, is here: https://www.printables.com/model/995672-pipkey-bluetooth-midi-instrument

A magnetic-themed, MIDI-based instrument inspired by the cello and designed to be portable, intuitive, and tactile.

(The name is a work in progress…)

This device is designed around my big skeleton hands and likely won't fit many other people.

It uses four buttons and three positions to play notes on a scale (that can be altered in the code).  Magnetic pogo pins along a linear track with grounding connections (inputpullup) that snap onto the main hand communicate the main hand's current slide/fret position. The arm requires no active electronics. There's also a PSP joystick that's used to shift the notes up or down an octave and adjust the velocity of the MIDI signal.

Assembly Notes:

• Please DM me if you're genuinely interested in building this and I'll write some elaborate instructions :)

Printing Notes:

• Printed in PLA at 0.2mm layer height with Tree Supports
• Print 4x ‘Button Caps’ (Consider using something more durable than PLA, like PETG or enhanced PLA)

Materials:

• PLA
• Solid Core Wire/Solder (for soldering to the pogo pins & kailh keys)
• ½ Breadboard
• 4x Kailh Choc keys (plug-shaped top)
• PSP Joystick
• 40mm Stretchy fabric
  • 2x segments for securing the rail to your arm
  • 1x 20mm segment (cut in half) for the back of the main body
• Arduino Pro Micro (or any 32U4-based microcontroller)
• Android Phone with FluidSynth (+ appropriate connection cables/adapters)
• 3x 6x3mm Cylindrical Magnets
• 6mm diameter 150mm length High-Speed Steel (HSS) rod. Example
• 5x M3 Nuts
• 2x M2 Nuts
• 3x 8mm M3 Screws
• 2x 12mm M3 Screws
• 2x 10+mm M2 Screws
• 4x Segments of a 20x20+mm Protoboard. Example (The small, slim option)
• A set of male/female (1x/3x) Magnetic pogo 3-pin connectors. Example
  • Must be 4mm tall, 4x15mm footprint (in the example, snip the side tabs off)

Future Improvements:

• Wireless/battery powered using a Teensy 4.1 and Speaker/3.5mm Jack as output instead of using MIDI and a phone with FluidSynth.
• Using 4-pin magnetic pogo pins set for 7 positions instead of just 3.  This would open up the device to a more fret-based approach instead of simple 3 sets of 4 ascending notes.
• Vibration LRA for more feedback about shifting between positions
• Buttons that fit better and don't fall off a lot.
• Maybe the use of a Wii Nunchuck in the right hand for even more controls/effects.