3D printing has become commonplace in the hardware industry, but because few materials can be used for it easily, the process rarely results in final products. A Swiss startup called Spectroplast hopes to change that with a technique for printing using silicone, opening up all kinds of applications in medicine, robotics and beyond.

Silicone is not very bioreactive, and of course can be made into just about any shape while retaining strength and flexibility. But the process for doing so is generally injection molding, great for mass-producing lots of identical items but not so great when you need a custom job.

And it’s custom jobs that ETH Zurich’s Manuel Schaffner and Petar Stefanov have in mind. Hearts, for instance, are largely similar but the details differ, and if you were going to get a valve replaced, you’d probably prefer yours made to order rather than straight off the shelf.

“Replacement valves currently used are circular, but do not exactly match the shape of the aorta, which is different for each patient,” said Schaffner in a university news release. Not only that, but they may be a mixture of materials, some of which the body may reject.

But with a precise MRI the researchers can create a digital model of the heart under consideration and, using their proprietary 3D printing technique, produce a valve that’s exactly tailored to it — all in a couple of hours.

Although they have created these valves and done some initial testing, it’ll be years before anyone gets one installed — this is the kind of medical technique that takes a decade to test. So in the meantime they are working on “life-improving” rather than life-saving applications.

One such case is adjacent to perhaps the most well-known surgical application of silicone: breast augmentation. In Spectroplast’s case, however, they’d be working with women who have undergone mastectomies and would like to have a breast prosthesis that matches the other perfectly.

Another possibility would be anything that needs to fit perfectly to a person’s biology, like a custom hearing aid, the end of a prosthetic leg or some other form of reconstructive surgery. And of course, robots and industry could use one-off silicone parts as well.

There’s plenty of room to grow, it seems, and although Spectroplast is just starting out, it already has some 200 customers. The main limitation is the speed at which the products can be printed, a process that has to be overseen by the founders, who work in shifts.

Until very recently Schaffner and Stefanov were working on this under a grant from the ETH Pioneer Fellowship and a Swiss national innovation grant. But in deciding to depart from the ETH umbrella they attracted a 1.5 million Swiss franc (about the same as dollars just now) seed round from AM Ventures Holding in Germany. The founders plan to use the money to hire new staff to crew the printers.

Right now Spectroplast is doing all the printing itself, but in the next couple of years it may sell the printers or modifications necessary to adapt existing setups.

You can read the team’s paper showing their process for creating artificial heart valves here.