The people who know about the technology of 3D, understand how much time we invest in the process of printing an important project. Usually that process take a lot of hours.
Now, imagine that after the whole process and after a dificult evaluation of quality, you recieve a bad notice your model or prototype have errors. And now, the piece , that took you many hours, has to be printed again. To front this problem, the NASA has been developing a new technology that allows you to verify the quality of your pieces while its printing, in real time. So that allows you to detect problems before the process its fisnished, giving you a chance to adjust the process of fabrication and not to wait the process to be finished.
If you want to know about this technology, you can enter into this link: https://technology.nasa.gov/patent/MFS-TOPS-70
If you want to know about the technologies that exist for additive manufacturing, also knows as 3D Printing, you can enter into this link: http://fablab.esan.edu.pe/es/aprende/548-3dnivel-i
If you want to know about 3D printing and, the most frequently problems and how to afront those, we recomend you to take: http://fablab.esan.edu.pe/es/aprende/530-impresion3d-n2