Dan Gelbart

Master prototyper down to 1 micron. https://makezine.com/2015/03/20/18-lessons-smart-prototyping-self-made-billionaire/

1. Smooth surfaces - [1]. Scraping and lapping. Hydrodynamic = zero friction, zero wear. Reversal method - with a dial indicator - to get straightness or flatness or runout of an object. Can separate roundness from runout. Reversal method is critical to precision and metrology.
2. Strength vs stiffness - 2 bars held with rubber bands are stiffer then a single one as long as the 2 bars don't separate. [2]. Clamping vs set screw - we use this on the heavy tractors:)