Economist Magazine hailed Additive manufacturing (AM) as “Third Industrial Revolution”. AM also features prominently in Factory 4.0. It has been practiced in one form or other for more than 5000 years. A pyramid in Egypt was built at 2800 BC using layer-by-layer construction. Modern versions for this technology are around for almost three decades. The first patent on steriolithography was issued in 1986 to Charles Hull. In many ways it is “back to the future”

Presently, there are several 3-D printing machine manufacturers using wide range of raw materials from wax to metals using various techniques. They are also making products from food to fashion. Even AM machine capable of remote manufacturing is now possible.

However one of the critical needs is “Certify as you build”. Due to relatively low volume production, conventional statistical quality control is difficult. In-situ diagnostics and quality assurance is needed and that is relatively unexplored field. In-situ optical diagnostics and its capability to integrate with the process control is a prudent alternative. New optical Sensors are being developed to control product health and geometry using imaging, cooling rate by monitoring temperature, microstructure and composition using optical spectra. Ultimately these sensors will enable one to “Certify as you Build”. Recently the author and his group have developed a technique to analyze the plasma spectra to predict the solid-state phase transformation, which opens up the new horizon for the materials processing and manufacturing.

Mathematical model developed for the process includes most of the physics but need substantial computing time. An effort needs to be made to develop surrogate models, which can converge within 10ms to enable the process control. Flexibility of the process is enormous and essentially it is an enabling technology to materialize many a design. Conceptually one can seat in Santa Fe and fabricate in Sheffield. This paper provides an overview of the past history, present status and future needs and potential.