content: 3D printing is a terrible way to mass produce things. We already have a whole bunch of very scalable, well tested, economical mass-manufacturing techniques. 3D printing trades off per-unit time and cost against setup cost, so it's great for one-offs. It still falls far short of traditional mass production at any reasonable quantity, because the setup cost falls off rapidly when amortized over many units, the time to produce a single 3D printed part is huge by comparison, and the quality of 3D printed parts is usually fairly poor.