MX MIDI Guitar

A guitar-shaped USB MIDI controller with key switches, selectors and motion input. It controls a host instrument; it is not a standalone sound generator.

Documented physical build · Sources reviewed 11 September 2026

CAIBI assessment

A detailed route to an expressive USB MIDI controller if you are comfortable with extensive wiring and printed mechanical parts. Resolve missing parts before starting the enclosure.

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Cost and commitment

No complete current basket is verified. The overview showed several unavailable parts at review; stock labels differ across guide pages, so check the seller directly. Replacements need mechanical fit checks. Add printing, consumables, cables, tax and delivery to any component subtotal. Optional lighting is excluded from this base-controller summary; the source lighting route also needs a Feather, 35-NeoPixel strip, slide switch and 500mAh battery.

Lead and build time

No independently verified build time. Allow separately for printing, a substantial wiring session, mechanical fitting and firmware/host debugging.

Parts and fabrication

Grand Central M4 Express, LIS3DH accelerometer and twelve MX switches
Two 10k panel potentiometers, mini potentiometer, two lever microswitches, eight-way selector and two toggles
USB extension, proto board, wiring, fasteners and the source whammy hardware
Printed body, neck and control parts in the exact quantities listed in the creator files

The source supplies STL and editable STEP files, print quantities and support-free FDM guidance. It describes a roughly 250 × 210 × 200 mm printer envelope; check the longest neck part against your machine. Use the source quantities rather than scaling the guitar to fit.

The linked source BOM and files control exact quantities, dimensions and revision. This summary is not a replacement fabrication file.

Assembly and test route

Follow the creator’s detailed instructions at each stage. The sequence below identifies the decisions and checks that connect them.

Reconcile the creator BOM with current availability, including switches, proto board and potentiometer dimensions. Keep the circuit and enclosure revision together.
Download the source STL/STEP set and check every quantity, printer envelope and control cutout before printing. Test-fit controls before completing the assembly.
Follow the creator circuit diagram and illustrated wiring sequence. Label the harness so the selectors and switches can be checked individually.
Install the guide’s CircuitPython code and required libraries on the Grand Central M4. Verify compatibility with the selected firmware version before closing the body.
Test each note and release, selectors, potentiometers and motion control in a MIDI monitor, then map the host instrument. Record stuck notes and missed or duplicate events.

Where AI helps

AI can reconcile the BOM, explain the CircuitPython mapping and help troubleshoot MIDI messages. You must check wiring, mechanical travel, solder joints and every input.

UK and US purchasing

These are specific sourcing routes, not a verified complete basket. Check exact variants, stock, shipping destination, tax and delivery before purchasing.

Region	Part or kit route	Scope
UK	Grand Central M4 board listing ↗	Linked item only. Delivered total and lead time unverified.
US	Grand Central M4 board ↗	Linked item only. Delivered total and lead time unverified.

Benchmark this project

Use the MX MIDI Guitar prompt. Compare what different models deliver, then add what happened when you tried it.

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CAIBI adaptation · Prompt 1.0 · Project source

Prompt for MX MIDI Guitar

CAIBI project benchmark: MX MIDI Guitar
Prompt version 1.0

Help me build MX MIDI Guitar using the existing creator project at https://learn.adafruit.com/mx-midi-guitar. This is a CAIBI benchmark adaptation of the project build brief, not a claim about how the creator used AI.

Project context:
- A guitar-shaped USB MIDI controller with key switches, selectors and motion input. It controls a host instrument; it is not a standalone sound generator.
- Build context: Grand Central M4 Express, LIS3DH accelerometer and twelve MX switches; Two 10k panel potentiometers, mini potentiometer, two lever microswitches, eight-way selector and two toggles; USB extension, proto board, wiring, fasteners and the source whammy hardware; Printed body, neck and control parts in the exact quantities listed in the creator files.
- Fabrication scope: The source supplies STL and editable STEP files, print quantities and support-free FDM guidance. It describes a roughly 250 × 210 × 200 mm printer envelope; check the longest neck part against your machine. Use the source quantities rather than scaling the guitar to fit.
- AI role: AI can reconcile the BOM, explain the CircuitPython mapping and help troubleshoot MIDI messages. You must check wiring, mechanical travel, solder joints and every input.
- Known limitation: Source-based desk assessment only. No CAIBI physical build, current substitution approval or complete delivered UK/US cost.

Read the source first. Use its published design, files, dimensions and parts as the baseline; do not redesign it unless a missing detail requires a clearly labelled proposal. If you cannot access a source or verify a revision, say so.

Provide one practical build package:
1. Design and files: explain the source design, link the original editable files, and identify missing files or modifications.
2. Parts and fabrication: give quantities, exact variants and compatibility, plus a cutting or printing list where applicable. Preserve source dimensions; flag anything unconfirmed.
3. UK and US purchasing: direct product links, checked dates, stock, pack sizes, taxes, delivery and regional costs. Mark unverifiable details as unknown; do not invent links, prices or availability.
4. Assembly: an ordered guide covering fabrication, fitting, wiring or software as applicable, setup, checks and troubleshooting.
5. Cost and time: separate parts, fabrication, delivery, hands-on time and machine time, with assumptions and exclusions.
6. Function and ease: a test plan for the project's stated purpose, likely difficulties, required skills and any corrections or limitations.

Keep source facts, your proposals and items needing physical verification distinct. An estimate is not a measured build result. Do not claim to have built or tested hardware. Include failed attempts and omissions. If a section does not apply, say why.

Use the source as accessed during this run and record its revision or access date. The prompt is fixed; the linked source can change.

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Benchmark results 0

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Source evidence and limits

SOURCE: linked creator documentation and product descriptions.

CAIBI: the desk assessment above, based on those documents. Source-based desk assessment only. No CAIBI physical build, current substitution approval or complete delivered UK/US cost.

BUILDERS: no first-hand build result is claimed by this assessment.

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