Here's the type of machine that Staples will be using. It makes models by building up layers of paper glued together. It looks like it won't be capable of the fine details that some of the other methods offer, but it's supposed to be a lot cheaper. You can even print colors as the model is built.

https://www.youtube.com/watch?v=s2h1k0cpgzQ

Steve S

SoftImage will be using "SI Units". These can be defined as anything. Just units. It appears that the intent is 1 SI units is actually 10cm. The input fields accept math functions, so you can define with that in mind. Alternatively, you could just work as 1 unit is 1 unit, then figure out the scale factor when the time comes.