[JKCalhoun]

That's the way I see it.

Just as an example I am familiar with: so many people appear to begin a project like a MAME cabinet with SketchUp.

I like "Cardboard Assisted Design" and have literally built several MAME cabinet prototypes in cardboard where iteration is easy with merely a box-cutter knife.

When the ergonomics and part-fitting is "go", I take measurements from the cardboard proto and move to wood.

Designing acrylic parts for later laser-cutting I have also used "CAD" for prototyping — sometimes even flat-bed scanning the chipboard prototype and then moving to a vector drawing app to overlay the laser-friendly beziers.

Even for PCB layout I often will laser-print the PCB as a final sanity check: punching holes in the paper and shoving the actual electronic components in to see that everything will fit before I send the file off to Taiwan.