I received my first Shapeways 3D print (SW), and can now personally compare with i.matrialise (IM). I had ordered a big 61'6" Interurban: carbody, floor, and 2 bogie frames. As material, I choose Fine Detail (FD). Shapeways FUD is not applicable for such large models.
Here is my personal "Benchmark":
Price: The model in FD is almost exactly the same as for IM's Prime Gray (PG).
Quality: I am very pleasantly surprised by the quality. The roof curves are perfect, with no steps. The ultra-fine grooves (spaced .58 mm) are well rendered, without horizontal lines. The floor with resistors, compressor and air tanks has been well executed. Likewise, the bogies.
Fit: The approximately 22 cm long model of SW is about 2mm shorter than the same model in Prime Gray from IM ...
Material: Now the downsides. FD by SW is clearly less robust than PG by IM. A truck frame had already come broken in the shipping box. When cleaning with water I broke also the graceful pilot. It consists of 1x1 mm strips. Presumably, they are unstable by wax inclusions. The chassis was warped, but you can unwarp with hot water. The chimney, about 2mm thick, however remains intact.
Treatment: SW "cleans" the models from wax before shipping with ultrasound. Wax is used as contrast material. But the pieces still contain enormous amounts of wax that you can feel (and smell). Especially with very detailed models with much relief there is too much wax whose removal is still a mystery to me. I used textil cleaner. This washes out the wax, but it remains hanging on the surface as a white powder and must be laboriously removed with a toothbrush, eraser pen and water baths. As long as the FD parts seem pretty clear and smooth, they contain wax. Only when they are milky white and rough, they are paintable. Dewaxing is a real torture. Does anyone have advice? I'm experimenting also with oven cleaner, WD40, vinegar and salt ...
Design Recommendations: I could glue the pilot again, but after this photo he broke again. In the end, one would have to draw for FD other than for PG: thin structures with long 1x1 mm posts are not possible. Neither pilots nor bogie truck frames in FD. FD also warps easily.
Conclusion: FD is very well suited for monolithic detailed car bodies, but without thin extensions. Forms with many curves are very well reproduced without steps. When drawing, you must consider that FD is much less stable than PG. For thin free-standing structures, one should not venture into FD, even if you stay within the material tolerances. Wax inclusions are obviously a problem. The removal of wax is also a fundamental problem and actually the biggest drawback.