We've replaced Cream Robust with Grey Robust as of today. We did this to give the Robust material a shot in the arm because several community members requested a different color. The price remains the same.
The Grey Robust material is an ABS plastic made with Stratasys' Fused Deposition Modeling (FDM) process. If you look at the material closely you can see layers in it. This has lead the material to be a under appreciated one. But, I will speak out now in defense of Grey!
ABS plastic is a very strong material. The material is also very durable. It is also not flexible so makes for good housings, structural parts and engineering parts. The biggest advantage that Grey Robust has however is that it is the most dimensionally stable material out there. If you need for something to be precisely the right size, then Grey Robust is the right material for you. We suggest it for things like robot parts and for use by 'makers' and engineers. Please tell us what you think of the new color and give us feedback if you decide to use this material. You can check out more data on the material here.
I don't know how well of a choice that model was, when you discuss build layers. It almost makes it sound like all the lines are build lines, but I presume the four lines that travel along the model are designed in?