(Commonly referred to as "MFOS") A manufacturer of circuit boards for modular synthesis, plus kits for a few products. The company is located in Colorado in the USA. Boards for a wide variety of functions are available, as well as a few kits for complete monophonic synths, and some kits and items specifically for educators and classroom use. MFOS also offers most of the less-common parts that their designs call for, although the customer can obtain them from elsewhere if desired. Each board has a corresponding project page on the Web site with assembly and test instructions, as well as hints and tips for use. The circuit boards are format-agnostic; for most boards the project page provides a suggested panel layout, which is usually in MU (Dotcom) or Eurorack format. MFOS's proprietor, Ray Wilson, is a frequent contributor to the Synth-DIY mailing list, and a number of possible modifications to MFOS designs can be found there.
MFOS proprietor Ray Wilson died July 23, 2016. MFOS was closed down for a while after that, but Ray's wife Debra re-launched it, and it is doing business again as of 2020.