In Conway's Game of Life, the first self-constructing machine used this principle. It has two construction arms, and the recipe for them to create new copies of

In Conway's Game of Life, the first self-constructing machine used this principle. It has two construction arms, and the recipe for them to create new copies of themselves is encoded in gliders and bounced back-and-forth between them. This turned out to be much simpler than building any kind of storage device. https://conwaylife.com/wiki/Gemini https://conwaylife.com/wiki/Gemini