Possibly something along the lines of Eurocards (as people who make synthesizers call them), which is based around Eurocards -- still used in industry. https:/

Possibly something along the lines of Eurocards (as people who make synthesizers call them), which is based around Eurocards -- still used in industry. https://en.wikipedia.org/wiki/Eurorack https://en.wikipedia.org/wiki/Eurorack (Unless you just meant a less-than-42U 19" rack, which is easily available. You can buy 19" racks as small as 6U.)