Strumli - A Single String Instrument
A 3D printed Single String Instrument
Intro
Strumli is a quirky, 3D-printed instrument inspired by the TuneFast harp. Designed to play a single song at a time, it combines engineering, creativity, and fun into a unique, customizable prop.
Concept Origin
Strumli was inspired by the TuneFast harp, a clever design by Adam Kumpf and Maura Atwater. While their project focused on playing musical scales, I took a less practical approach: creating a quirky instrument that plays a single song at a time. The idea was to combine curiosity, engineering, and fun into a unique prop. Strumli shares the same fundamental concept but adds its own twist, making it a playful experiment in sound and design.
Design & Development
Online Piano Interface
To control Strumli, I built a web app using HTML, JavaScript, and CSS—skills I learned on the fly thanks to a CodingNepal tutorial (link here). The app lets users click notes to play music and displays relevant information. Hosting it on Netlify made sharing simple, and the code is available on GitHub for anyone to explore or improve.
Physical Design
The soundboard is interchangeable, allowing users to swap songs easily. Early prototypes included a pull-back toy concept, but I simplified the design to focus on functionality. The final housing features a clean “pill shape” that fits nicely on a shelf. The design balances aesthetics and practicality, with features like V-groove bearings to manage string tension and prevent mechanical failure.
Prototype & Build
Soundboard Design and Assembly
The soundboard uses V-groove bearings to transmit tension between string segments, avoiding issues with the capstan equation. Strings zig-zag across the board, creating a continuous path for up to 7–8 notes. Assembly involves threading bolts, installing guitar tuners, and stringing the instrument. High E strings work best for tuning, while nylon strings can reduce stress on the plastic components.
Build Instructions
Assembly is straightforward:
Thread bolts with bearings and washers, secure them to the soundboard.
Install the guitar tuner and magnets (optional).
String the instrument, zig-zagging the notes, and set tension with a guitar tuner.
Final Result
Strumli is a fun, functional project that combines engineering and creativity. The design is complete, but I encourage others to contribute new soundboards to expand the library. Join the Discord server to share ideas, designs, or ask for help. Whether you use it as-is or adapt it into something wild, Strumli is a playful experiment that invites collaboration and creativity.
