To make models for Shapeways full color 3D printing do the following.
1. Sculpt in the normal way using DynaMesh or Zremesher. Try to make sure sculpting is completely done before moving on to the next step. It's not mandatory that the sculpting be done, it just makes things easier because if sculpting needs to be done that requires any DynaMeshing the UVs will be lost and these steps will need to be repeated.
2. Make a high resolution sculpt and PolyPaint the details onto it.
3. Make a duplicate for doing a projection.
4. Set Zremesher Target Polygons Count to 100, Adaptive Size to 0 and Curves Strength to 0 and Zremesh the duplicate. Keep in mind that Zremesher will not weld shells together like DynaMesh does.
5. Close any holes that appear in the Zremesher result if you use Zremesher.
6. Save a Morph Target and subdivide and project the PolyPaint from the original. Use the Morph brush to help correct any projection errors or if you just want the PolyPaint click the Morph Target Switch button.
7. Add UVs with UV Master and do a New From PolyPaint to create the texture maps. I usually use 4096 map size unless it's something small.
8. Do any posing that needs to be done.
9. Decimate using Decimation Master with Preserve UVs. Shapeways wants you to stay under one million triangles, but I once accidentally uploaded a 1.4 million triangle model and it worked. I don't know what the actual limit is. If you have multiple SubTools they all need to add up to one million triangles combined.
10. Go to UV Map -> Adjust and Flip U and Flip V. The U and V need to be flipped because Shapeways' server software Mesh Medic flips them upon upload.
11. Do these steps for each SubTool if there are multiple SubTools.
12. Once decimated use 3D Print Exporter to save as a VRML. I usually use the default settings. This will output a geometry file as well as a texture map. If multiple subtools were involved they will all be combined into one geometry file, yet each SubTool will have its texture map outputted as a separate image file.
13. The last step is to zip the resulting VRML files into one zip file. Make sure there are no directories incorporated into the zip file when zipping. It has to be just the file without any directories added. In Microsoft Windows operating system I usually just select the files in Windows Explorer and then click the Zip Button found under the Share tab. The resulting zip file needs to be under 64 megabytes.