To create their contraption, the team turned to 3D printing. They used a custom 3D printer called MultiFab to make the T-shaped gizmo, which has a small circular part that changes color when the T's crossbars stretch. MultiFab did everything, from printing the device's thin, sensor-laden plastic skin to depositing and curing the liquid that serves as its semiconductor. "In nature, networks of sensors and interconnects are called sensorimotor pathways. We were trying to see whether we could replicate sensorimotor pathways inside a 3-D-printed object. So we considered the simplest organism we could find."

Right now, the typical 3D printer is a tool for making plastic objects. Assembling them in layers according to a pre-programmed plan, the printers can quickly make weirdly shaped parts, but they're often limited to working with just one material at a time. Additive manufacturing, as 3D printing is also known, offers so much more. A new printer, created by MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL), can print up to 10 materials into a single object --and incorporate other, finished parts directly into the design-- all at a fraction of the cost of complex industrial 3D printers Their new printer, known as the MultiFab, is a system of systems. A central computer runs the printing program, but as it does so it receives feedback from 3D scanners and machine vision, which map the object as it's being made, allowing the computer to adjust the printing process and materials accordingly.

Most 3-D printers use a single material to fabricate objects. For consumer 3-D printers, that generally means some kind of plastic or resin. But using only one kind of material means 3-D printers are limited in the kinds of objects they can create. There are 3-D printers that can use multiple materials, but they can cost tens or even hundreds of thousands of dollars, putting them out of reach for almost everyone besides engineers and developers. A team at the Massachusetts Institute of Technology's Computer Science and Artificial Intelligence Laboratory wanted to find a way to create a more affordable multi-material 3-D printer, and thus the MultiFab was born.

But the technology is still far behind in reliably producing a variety of useful objects, with no assembly required, at a moderate cost. In recent years, companies have been working to tackle some of these challenges with "multi-material" 3-D printers that can fabricate many different functional items. Such printers, however, have traditionally been limited to three materials at a time, can cost as much as $250,000 each, and still require a fair amount of human intervention. But this week, researchers at MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL) say that they've found a way to make a better, cheaper, more user-friendly printer. In a paper accepted at the SIGGRAPH computer-graphics conference, a CSAIL team presented a 3-D printer that can print an unprecedented 10 different materials at once by using 3-D-scanning techniques that save time, energy, and money.