Most of the plastic parts you are familiar with have been made by a process called injection molding, whereby plastic is injected into a cavity in a mold and a plastic part is extracted after cooling. The process of injection molding has many limitations of it's own and designs must be made to conform so as to be moldable, strong, and not crack or have defects. We could write an entire paper on these constraints, but suffice it to say they are very much different and share