3D-Printers have given us all the unprecedented ability to manufacture mechanical parts with a very low barrier to entry. The only thing between your idea and its physical manifestation is the process of designing the parts. However, this is actually a topic of incredible depth: Design engineering is a whole discipline to itself, built on top of tons and tons of heuristics to produce shapes that are functional, strong, and importantly: well-manufacturable In this talk, I will present the rules for designing well-printable parts and touch on other areas of design considerations so you can learn to create parts that work first try and can be reproduced by others on their 3d-printers easily.