Manufacturers have spent decades learning how to make and assemble their products according to Lean principles. Through what has become a process of continuous change and improvement, they’ve succeeded in minimizing the use of space, materials, movement of work in process, and storage of finished goods inside their own companies. Physical inventories have been driven down to levels unimaginable a generation ago. Defects and other forms of waste have been similarly reduced. Lead times to make product are lower than ever.