Any method of producing molecules is referred to as molecular engineering. It can be used to make new molecules that don't exist in nature or are stable beyond a very restricted range of conditions on a very small scale, usually one at a time. Currently, this is a time-consuming technique that necessitates manual manipulation of molecules using instruments like a scanning tunnelling microscope. Because of the capacity to control the electrical, magnetic, and optical properties of molecule-based materials by selecting and altering their chemical constituents, molecular engineering is becoming a rapidly growing area. The controlled creation of highly ordered, crystalline molecular thin films is attracting a lot of attention because of its prospective uses in areas including solid-state photonics, microelectronics and biology. Protein engineering, the generation of protein molecules, a process that occurs naturally in biochemistry, such as prion reproduction, can be thought of as a precision type of chemical engineering. It does, however, offer far more control than genetic modification of an existing genome, which must rely solely on existing biochemistry to express genes as proteins and has minimal ability to make non-proteins.