There is a myth available about so called perpetual motion machine. That is a wonder machine, which will work without interruption after pressing the on button. Most engineers have come to the conclusion, that such a machine would violate the physical laws, or to be more specific the law of thermodynamics. What the engineers are not aware is, that perpetual motion machines are not invented as real machines, but they are the subject of stories about automation.
The concept is about a technology which doesn't need human work but works without human labor. The question is not how to build such a machine with the law of physics, but such a machine has to fit into economic context. To be more specific, a perpetual motion machine is something which the owner of a factory likes to buy to reduce the costs. What the owner of a factory is trying to achieve is to produce a maximum output with a minimum amount of work. This will increase his profit.
What is available in the reality are example of factory automation. The typical machine needs a lot of energy and is repeating the same task over and over again. A printing machine is an example, but a pizza making assembly line is also a good example. From a physical standpoint these machines are the opposite of perpetual motion machine, but from an economic standpoint they are. What automated factories have in common is, that the costs for the factory owner is low, and at the same time the factory is producing lots of pizzas. Each of them costs nearly nothing. It's surprising at which low price it's possible to produce goods if all the steps are fully automated.
Suppose a fully automated pizza line was installed in a factory, and the raw materials are available. From a users perspective such a device is a miracle. The user can enter who many pizzas he like to eat, and after entering the number of 100k the start button is pressed. The machine won't stop until all the units are created. No further interaction is needed. The most interesting point is, that such a workflow is available in the reality. That means, real pizza making factory can be visited and they are used to produced food for the population.
To understand fully autonomy machines better we have to ask for potential bottleneck. What all these devices have in common that they need something as input. Its electricity plus raw materials. If no energy is available and no cheese is there, the machine won't work. The interesting point is, that these input materials are endless. Producing energy at low costs is an easy task and producing tones of cheese is also a solved task. If the production of raw materials is combined with fully autonomous assembly lines the result is a fully automated economy. Literately spoken, such a system can produce endless amount of goods for zero costs.