The ability to manufacture goods efficiently and with superior functionality has long been a key determinant of economic success for individuals, enterprises and societies.  Contrary to popular perception, most innovation takes place through an evolutionary process in which pre-existing elements are recombined in surprisingly useful ways, rather than as a radical departure from the status quo.  This is true of innovations in apparatus and methods and also in manufacturing techniques. 
The history of manufactured goods spans a long series of transitions across materials (from wood, stone and leather to gold, copper, bronze, iron and steel and on to various synthetic materials including among others man-made polymers.  Likewise, the techniques of manufacturing have evolved from the preparation of individual items through the development of interchangeable parts, moving assembly lines and various photolithographic techniques for the preparation of circuit boards, integrated circuits and micro-electromechanical (MEMS) systems. 
MEMS systems predominate among mechanical devices at the micron scale and typically involve the bulk addition and removal of materials in serial fashion from a single substantially planar substrate.  Traditional machining and fabrication practices are readily applicable to devices from centimeter scale up to meters (e.g. large machine tools and dynamos). 
While these developments have led to a remarkable abundance and variety of products, one that would astound the most prescient individual of a century ago, there remain apparatus and systems that are persistently difficult, time-consuming and consequently expensive to manufacture.  In particular, manufacturing at the millimeter scale, remains challenging for a variety of reasons.