Art machines are an evolution of a core tinkering activity, Scribbling Machines. These playful contraptions use a single hobby motor, a AA battery, and a hot glue stick to produce an erratic motion. When mounted on a body with a pen attached, they move and giggle to create chaotic and beautiful drawings.
Add a micro:bit or a LEGO WeDo motor and the results are quite different, both in terms of the process that you go though to build them and the types of drawings that they produce. By using a motor or servo, you can program speed, direction, and even the duration of movement. Code affords the opportunity to systematize the testing of variables and iterate on your design, which can result in a range of drawings with different qualities or appearance.
Microcontrollers programmed in MakeCode or Scratch even allow for the possibility of incorporating linkages and sensors into your machine, radically changing the resulting drawing.