@IndieArt, from artist perspective it all seems obviously but you would be amazed with how much different interpretations people can come up with reading this sort of text. Most artists understand that a 3D product needs to be part of some form of production (value added), be part of some bigger product (incorporated).
But read this text you can find next to 3D print models, “Royalty Free License allows you to use the product without the need to pay royalties or other license fees for multiple uses, per volume sold, or some time period of use or sales. Products published with this license may not be sold, given, or assigned to another person or entity in the form it is downloaded from the site, but can be used in your commercial projects multiple times after paying for it just once.
This is, however, a non-exclusive license and the product remains the property of a seller for further distribution. Please, refer to legally binding General Terms and Conditions to learn more about Royalty Free License, other types of licenses and general rules applicable to all products.”
That actually seems to imply its ok to sell 3D prints (no need for royalties per volume sold, or some time period of use or sales), but not sell the product as downloaded from site (the 3D files).
To me it looks like the 3D print needs to be part of some project/bigger product (for example propellers of a quadcopter or something) and its not allowed to sell a design/copy strait from 3D printed files, for example a figure of darth vader.
So you could say a 3D print is a part that can be incorporated and get to be a new product for sales, but a 3d print can also have a design that is protected and have a need for royalties per printed copy sold.