https://abacusynth.eliasjarzombek.com/
This repo contains code for the web page. For the Ableton Plugin, see here. For the hardware device, see here.
The Abacusynth is a synth inspired by an abacus and the interaction is centered on placing shapes on rods. Each rod is set to a frequency in the harmonic series, and each shape represents an oscillator oscillating at that frequency. The different shapes represent the oscillator's wave type (sine, square, triangle, sawtooth).
Place shapes on the rods to start producing sound. Shapes on the lowest rod produce the fundamental frequency. You can change the note by pressing the keys asdfghjk.
Drag shapes will move them from left to right or from rod to rod.
If holding the ALT or OPTION key on your keyboard, dragging a shape adjusts it's vibrato rate (dragging up/down) and depth(dragging right/left). This will cause the shape to move on the rod.
If holding the SHIFT key, dragging adjusts the shape's size panning speed which correspond to the sound's volume and panning speed, respectively.
Click "Randomize" will clear the current state and randomly generate shapes.