A group of MIT students have built a scanning system that allows 3D printers to restart prints after a failure. After each layer the laser scans the object, senses the shape, and records the state of the object. Over the course of the print it creates a point cloud model of the object and then compares it with the actual 3D model.
When the print fails the program simply fills in the missing pieces and prints out the missing parts. The students are planning to open source the project and have no plans to commercialize it.