I have figured out a way to be able to get textures/decals to render to your 3D PDF.  The last time I was here searching for a way I found nothing to help.

If enough people is interested or if this is still an issue, which I believe it is as I have been in contact with SW and they say they don't support it.....but they do..you just have to do this work around...Reply here if this would be helpful to know.

For an example this was out of SW-

http://www.ghielectronics.com/downloads/3DPDF/FEZ_Spider_Mainboard_3D.PDF