We spoke to Tim from SOMA about Enigma, the latest instrument from them controlled with metal objects rather than conventional knobs. The surface responds to coins or other metal pieces, and parameter changes happen where the printed lines cross.
Enigma contains eight engines, including drum engines, noise-based sounds, arpeggiated parts, tonal material and preset-specific effects. Tempo can run internally, and it can synchronise with other gear. The same coin position produces the same result, though finding that point can be imprecise. Metal size matters: smaller pieces may not drive a parameter to its full range, while larger pieces can affect several parameters at once.
Tim had some great ideas about using templates and stickers to create physical presets. Markers or templates can help return coins to fixed positions - neat.
More Info: https://somasynths.com