Made for Me has recently released not another guide, technically, but the results of their Design & 3D Printing Survey. The information therein certainly does serve as a guide of its own, however, offering up information regarding desktop 3D printing users, commercial users, and those who send their 3D printing needs out to service bureaus. Desktop operators showed that they use 3D printing mainly for appearance rather than functionality, while commercial operators used it for both, and those sending work to service bureaus offered up a strong mixture. As for challenges, they saw price and materials as big obstacles, along with a need for more education in 3D printing, greater transparency, and better software tools. Read more at 3DPrint.com: https://3dprint.com/146456/made-for-me-designer-survey/