FAC-System is a mechanical construction set, invented by Swedish artist Mark Sylwan in 1952. It uses mainly metallic parts, and extensively uses 4 mm steel rod. The company continued in business as of 2013, supplying kits stated to give industry a basic construction system which gives the same freedom in 3D design as is available from the drawing board and CAD/CAM. Kits are suitable, and priced as, for laboratory work and teaching.
References
FAC-System Wikipedia(Text) CC BY-SA