Overall, designing physical things, building working prototypes of novel stuff, and designing factories for large scale production are each an extremely vast do

Overall, designing physical things, building working prototypes of novel stuff, and designing factories for large scale production are each an extremely vast domain, at least as large as the whole of computer science and software engineering. They cover literally thousands of specialized disciplines and skills. Typically, people specialize in some facets of the above. And even seemingly simple products usually require teams of specialists with complementary skills to implement them starting from scratch. For some mainstream products which are well understood and are much discussed, it may be possible to take an existing open-source design, modify it, and then outsource actual fabrication to a contract fabricator. As a concrete example, one can take a complete design of a small quad-copter [1], learn as much as one wishes about its real time firmware, about control theory and flight dynamics, about electronic circuits, motors and propellers, radio protocols and technology, etc, and get a taste of what it takes to replicate such a product. A completely different scenario is to focus on one relatively narrow technique which can be mastered in a reasonable time. For example, in this video [2], a legendary software developer makes in his garage a form for injection molding a plastic spoon. So one can do the same. Buy a small machine tool, and using on-line tutorials and help from strangers on-line,learn how to use it. After several years of tinkering it is possible to develop considerable skill without being a full time professional. [1] https://www.bitcraze.io/products/crazyflie-2-1/ https://www.bitcraze.io/products/crazyflie-2-1/ [2] https://www.youtube.com/watch?v=1KMuJzB3H8c https://www.youtube.com/watch?v=1KMuJzB3H8c