1. FRAME OF SCALE
CAD is a very powerful tool. You can design a football stadium… and you can design microfluidic channels. Unfortunately it’s very easy to lose your ‘frame of scale’. In other words, you don’t know how big… or small something is in real life. 3D Printing allows you to get a feel for the actual part in a way that you could never accomplish through a computer screen alone.
This works especially well for industrial designers. Their concern is how something looks, feels, and the overall experience of the device. CAD can try to fake reality by adding perspective, but it isn’t the real thing. When it comes right down to it, you need to have it in your hands. Not only that, once you print something out, you can modify it. You can sand, cut, machine, paint, melt, bend, etc… Whatever modifications you can think of to get it the way you want it. And then you can update CAD, reprint, etc…