Is there no such thing as a chain of custody for parts manufacturing? Crowd sourcing plastic parts from printers seems beyond naive. Do you know what goes into

Is there no such thing as a chain of custody for parts manufacturing? Crowd sourcing plastic parts from printers seems beyond naive. Do you know what goes into design of plastic molds or the repeatability and tolerances required? How do you quality control parts created from layers of hot glue? Plastic molded parts can rely on fundamental chemical understanding and tuned parameters of a molding machine.