FWIW, in considering how to get the molding master made, there were other non-Shapeways alternatives that would have worked fine. Most rapid prototyping shops have Stereo-lithography Apparatus (SLA) machines, like I mentioned, that can print at very high resolution and require little to no hand-finishing.
The process is pretty cool.
The Shapeways ultra and extreme detail acrylic prints are basically SLA (UV-cured resin), but they employ a moving print-head and they sell price tiers based on the resolution rather than always just printing at their best. It's sort of a hybrid SLA and FDM process.
Two shops in China quoted me at $80 to make each of the TMP scanner body masters using SLA, which was less than half what Shapeways charged me for that warped model I posted above. Also, unlike Shapeways, they are willing to guarantee their tolerances and even offered to take photos of the part with a caliper against it before shipping to me. And the part is ready in a day or two rather than weeks. Even with shipping from Asia, it would have arrived faster.
It just turned out that milling ABS on a CNC machine was going to be faster , cheaper, and give a better surface finish for this particular project, so I went with that.
But it's nice to know that there are other places where one can get high-res 3D prints made with a better cost-value proposition and hopefully better customer service. One of the places I looked at that specifically focused on 3D printing only was:
For their SLA process, they don't do online quoting, but they got back to me within hours on the model I sent them. For more sculpted (or non-machinable) types of project in future, I intend to give them or a similar company a try.