The advent of 3D printing completely revolutionized the prototyping stage of designing a new product. But while turnaround times for revisions or changes are now much faster with a 3D printer, they can be even faster if the printer fixes flawed prototypes instead of reprinting them from scratch.

Researchers from the Hasso-Plattner-Institut’s Human Computer Interaction Lab have built an improved 3D printer that now includes a built-in 3D scanner, as well as a milling head, for making modifications to existing plastic prototypes.

Design changes are made to a given product using a 3D modeler, but both the original and modified versions of the model are then fed into a custom piece of software that determines what exactly has changed, and what needs to be fixed.

The 3D-printed object in need of repairs is placed back inside the 3D printer, where a 3D scanner then analyzes it to determine the ideal orientation and passes of the milling head needed to remove the incorrect or unwanted areas. Once they’re gone, the standard 3D printing head can then get back to work to rebuild the parts of the prototype that needed modifications.

Not only does the process of repairing or modifying existing 3D-printed models speed up the prototyping process, it can also greatly reduce the need for raw materials. If you’re only fixing an area that makes up 5% of an existing model, you’re only using 5%of the plastic initially needed to 3D print it. So there’s savings to both speed and cost to this new approach, which is what every manufacturer loves to hear.