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One string finger guitar

Class: Musical Instrument Design (ME 116)

Year: Fall 2018

Goal: using concepts of acoustics and engineering, design, prototype, create, and test a musical instrument, and demonstrate its properties.


  • four different prototypes

  • less than $5 per instrument

  • always perfectly in tune

  • can play in any key of choosing


Technical Details

Inspired by a project by Makefast Workshop, the body of the instrument was created using OnShape. The model was then sliced in Tinkerine Suite and was 3D Printed using PLA on a DittoPro 3D Printer on Medium setting with 8% infill. The print took around 3 hours, and used 35g of filament. The faces of the same model was saved and rendered with Inkscape to be laser-cut using a Glowforge, and was glued together with acrylic glue, hot glue, super glue, and a lot of patience, time, and clamps. The model was then hand-designed on a piece of plywood, and machined using a bensaw and drills. The original 3D printed model was also edited to save filament and time.

The instrument uses two acoustical concepts: Equal Temperament and Frequency/Pitch. The concept of Equal Temperament is used to manipulate the length of the strings to correspond to each of the 8 notes in a full octave scale (WWHWWWH). The concept of frequency and pitch is used by changing the overall tension in the string, to change the instrument to be "tuned" to any key. The frictionless bearings and the usage of a single string made this possible.

The materials used for the instruments were either purchased on Amazon or acquired from the lab. The purchased materials are linked here (although any could be used): guitar strings, tuning pegs, bearings.

By nature, the acrylic model had the best acoustic amplification due to its resonating cavity, yet due to the fact that it was put together manually, was not perfectly "in tune". The 3D printed models, due to the low infill, also had some resonating cavity, and were the most precise in pitch. However, because solid plywood was used, the wooden model does not resonate as well without a guitar pick. Future adaptations could be to increase the resonating cavity, and to try different materials.

The poster for the End of the Year Show (EOYS) can be found here.

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