On a circular knitting machine, you crank a handle and a knit tube (e.g. for a scarf or hat, depending on the size of the circle) comes out. By going back and forth rather than all the way around, you can also create narrow strips of knit fabric on a circular knitting machine.
There is a write-up of the circular knitting machine as a good beginner tool for data visualization with textiles at: “Knot Hard: Accessible Textile Data Visualization with a Circular Knitting Machine”. DH + Lib 2024 special issue, “Making Research Tactile: Critical Making and Data Physicalization in Digital Humanities”. April 29, 2024.