Risograph printing is a type of duplication-printing technique and printer developed in Japan in the mid 1980's by the Riso Kaguku Corporation.
The "Riso" machine, is a type of mimeograph printing using master plates and ink drums, that can produce hundreds of duplications a minute in color. Often seen as a combination of a photocopier and offset printing press, the printer has been used by companies as an efficient and dependable alternative to color and inkjet printers.
From a first glance, the printer looks like any old photocopier, but inside is a color drum/plate system that allows for extremely fast printing. Each drum contains a large well of colorful soy ink that can only print on un-coated paper. While initial setup can take much longer than a normal printer, once the master plates are created, the machine can run thousands of copies fast and continuously, at very low cost.
For adding different colors and layers, a print can be run through the machine multiple times, each pass adding a new color based on the selected plate and color drum.
Today, the Riso Kaguku Corporation develops, maintains and distributes RISO Printer-Duplicator across the world. Companies can purchase or rent new or user machines directly from the Riso Kaguku, or through a distributer. Or if you just want to try out Risograph printing, there are hundreds studios across the United States that rent out time on their machines.