I have an STL file that, when I load it in Slic3r, looks fine, but somewhere in the actual slicing process, something goes wrong and parts of the model disappear.
That's the render on the left, and the slicing preview on the right. That big hole is the most obvious fault, but there are more little notches elsewhere on the model; you can see a couple on the bottom edge there. It looks like the program is ignoring some of the model's faces entirely. What's all that about?
The model passes every manifoldiness test I've thrown at it: Slic3r's, Meshmixer's, Blender's, and a couple of online services I've forgotten.The walls that go missing are pretty thin, but they're at least a millimeter at their narrowest point, so I think it should be thick enough for the printer to handle.
Here's a link to the STL file in question, on FileHosting.org, FlashHovering.stl.
I fixed it!
I had my extruder diameter set to 0.5 mm, and the narrowest point of the model was just a hair under a full millimeter, so I guess the program took it to mean that it should only put down one line of material. I made the walls a little thicker and now it looks fine.