Benjie Jiao from the Philippines started this fun project ‘SynthCard‘. This is what he writes: “During the lockdowns of 2020 to 2021, I taught myself electronics by building guitar pedals. Eventually, I discovered that I can create sounds without a guitar using the same components as my pedal builds–this led me into a Synth DIY rabbithole. Since then, I’ve been adding modules to my homemade modular synth.”
The SynthCard project is about building small synthesizer modules based on a creditcard-sized PCB. There are some standards set for layout, power connections and components and already a few modules are available. The idea is that you contribute your designs to this project.
Benjie also developed small synthesizer modules (i.e. not based on SynthCards) which gives you quite a quickstart for building your own modular synthesizer, including some Arduino based modules. Fun!