The pianola breeders are a series of patterns by Paul Tooke in 2010, based on a simplification and extension of the Gemini spaceship's construction mechanism. Tooke produced a number of slow-salvo-constructed patterns with superlinear growth, including a series of breeder patterns of previously unknown types. For some patterns, the Gemini's two construction arms were moved to a permanent stationary platform, using fourteen glider-loop channels instead of twelve.
Some of these breeder patterns remain difficult to classify unambiguously. For example, one pattern was designed to be an MSS breeder - a modified Gemini spaceship puffing slide guns which build lines of blocks. However, the slide guns produce both moving and stationary objects at a linear rate, because streams of gliders are needed to reach out to the construction zone to do the push reaction and build more blocks. The pattern could therefore be classified as a hybrid MSM/MSS breeder. Other breeder patterns utilizing slide guns and universal constructor technology are likely to cause similar classification ambiguities.