Hey, I have a model that was generated by a program. It looks fine, when I checked it in NetFabb it said it was made of several shells. The only problem is that I don't know if all the shells are overlapping. So I don't know if I'll get my whole model, or just lots of little bits I'd have to try and glue together. If someone knows how to check it, or turn it into one shell, that would be fantastic.
It looks like the tubes and triangles are all individual pieces. You can upload it and see how it looks in the preview. As long as that looks right, you will get one solid piece. You may have a problem with overlapping triangles (This will cause the Shapeways software to have issues). If so, in NetFabb, you can remove doubled triangles in the repair options.