You can now use the Sandstone 3D printing material. This material is exactly the same material as the Full Color Sandstone just with the color bit removed. 
The model depicted is MadebyDan’s Square platter. The platter would cost $74. Now you can now use this (our cheapest) material without having to convert or upload your model into VRML. Please do take into account that the material is fragile and does need to adhere to the design rules for the material.