Just as the laser printer delivered the benefits of a printing press to personal computer users more than 40 years ago, 3D printers have made it possible for individuals to turn digital designs into physical objects. Some printers cost less than US $1,000, and they can be used to create one-off objects or low-volume production of items.3D printed objects have one major limitation; it’s not easy to make them “smart.” Adding digital processors and other components remains a challenge, as does addi...