I'm not sure whether it is necessary to have a separate texture file when uploading X3D files to Shapeways for color printing. I tried Z-painting an image onto one of my objects in MeshLab and saving it in the X3D format in two ways, once with the colors assigned to the vertices and once with the colors transferred to the faces. Shapeways allowed me to upload both of these, but the preview shows nothing. I think possibly this is because they are showing the object as completely black, the color I assigned to the vertices before Z-painting. The colors do show up in MeshLab when I reopen the files, so I know they got saved.
Do I have to transfer my colors to a bitmap in a PNG or JPEG format to get them uploaded, even for X3D files? If so, does anyone know how I can do this?
Also on the subject of X3D files - could Shapeways give us the option of selecting the units (as with STL files)? I know the units are supposed to be metres, but if we could specify that we actually intend the units to be millimetres, that would be a way of getting around the "non-manifold" errors that occur because of a lack of precision.