Beyond Plastic: 3D Printers Are Now Printing Metal, Wood, Even Electronics

The challenge with 3D printing isn't the machine, it's the materials.

If you've used one of the current generation of desktop 3D printers, you'll have noticed there's a limit to what you can make: If you've always wanted a small, personalised model in cheap plastic, you're in luck, but that's about it.

That's set to change as 3D printer makers look to expand the available materials. At CES, Makerbot announce​d that by the end of this year it would offer composite materials of bronze, maple wood, and iron, while a host of projects are printing in new materials such as fake wo​od and carbon​ fiber.

One company at the forefront of this push is Vo​xel8, with its product based on the material science work of Harvard University res​earcher Jennifer Lewis. The Voxel8's Direct Write 3D printing technology pushes out "viscous paste" at room temperature using pneumatic or volumetric systems.

"It's effectively pushing paste out of syringes," co-founder Daniel Oliver told me. "The interesting thing with Direct Write is it expands the materials pallet, so it allows you to print out a large number of different materials on a similar hardware platform and has a wider band of materials it's able to print than frankly any other 3D printing technology I'm aware of."​

Its first printer, which costs $8,999, uses thermoplastic as well as conductive silver ink, letting you print electronics—Voxel8 likes to show off a fully-functioning quadcopter that was almost entirely printed in one go (the blades need to be attached separately).

​In Lewis's lab, she's printed lithium-ion batteries, epoxies, waxes, and even silks, said Oliver, as well as biomedical parts. "It's a really flexible platform for printing a lot of materials."

Indeed, the hardware isn't what's holding back more materials—the Voxel8 printer is a modular design, so you can simply pop in the parts you need, such as a fresh printer head for new materials.

"The actual innovation is in the material science behind the materials you're printing," said Oliver. "It's not trivial to get a conductive ink in the correct specifications. You need to have it controllable through a nozzle, but then not runny when you put it on a substrate, and also to have it be printed and curable at room temperature such that it doesn't need any post-curing so it can be printed together with another material."

Consider the conductive ink, a proprietary formula that's come from Lewis's lab. Mixed in with the silver is a solvent that evaporates at room temperature, curing the liquid—letting it harden into a filament. That means no heat or special light is required, and you can print electronics by programming in a channel for the ink and then covering it again with plastic before you carry on printing.​

The combination of materials that Voxel8 can do—plastic and conductive ink—is key, said Alex Chausovsky, a 3D printing expert at analyst firm IHS Technology. "This ability to print in multiple material categories—plastics, wiring, metals, ceramics, composites—all in one go, that I think is the next big trend that I would like to see happen over the next couple of years," he said.

That's already possible in some high-end, industrial printers. Stratasys released its first multi-material 3D printer way back in 2009. The Objet500 C​onnex, which costs a whopping $250,000, can print parts with both rigid and flexible sections, said John Jones, materials business group manager at the company. "Whether it be a brush, with a rigid handle and all the individual soft bristles, or a hand drill with the soft grip combined with the hard casing, for the first time designers and engineer could produce multi-material prototypes that look and feel like the final product at the click of a button," he said.

Its latest version, the Connex3, lets you print a piece using different materials—rigid and flexible, transparent and opaque—in a single print, choosing from thousands of substances. "To do this any other way would require printing each material individually in each colour and assembling them together, so as you can imagine this technology is a revolutionary timesaver throughout the product-design process," said Jones.​

Combine that with the Voxel8's ability to print in conductive inks, and we're on the way to a Star Trek replicator, notes Chausovsky, letting us push one button to print devices. "The reason that was so appealing is you walk up to the thing and say 'I want a cup of coffee' or 'I want an apple,' and it just makes it for you," he said.

But until material science catches up, we'll have to make our cups and coffee separately.

This story is part of The Building Blocks of Everything, a series of science and technology stories on the theme of materials. Check out more here: http://motherboard.tv/building-blocks-of-everything