The Tonus is a project underwent by Rohan Bumbra to see if purely analog synthesis of sounds was possible. The synth is purely based on the fundamental mathematics of music - Each cog you see is in a ratio with the first cog in a way that correlates to the frequency ratios of pitch. The instrument operates by spinning the cogs at the same speed, and then using a hammer to contact the cog. The resulting vibration would cause a vibration related to a pitch. This pitch could be altered by changing the speed of the rotation.
The Tonus was designed and hand-built from the ground up by Rohan.