Retailers

Austria
Raw Voltage (Assembled modules, DIY kits)

Germany
Munichen Audio (PCB sets)
Schneidersladen (Assembled modules)

United Kingdom
Thonk (DIY kits, PCB sets)
Signal Sounds (Assembled modules)
Elevator Sound (Assembled modules)

United States
Midwest Modular (Assembled modules)
Perfect Circuit (Assembled modules)