At the moment it is looking like the geometry is valid, but there is a bug in both the display mesher and OBJ mesh exporter (they share some common pieces so it is possible for them to both have the same bug) which causes the meshing to be wrong.

I'll see if I can track down what is wrong in the meshers.

- Michael

Yeah, this is definitely a bug that is common to both meshers. I haven't fixed it yet but I am zeroing in on it.

In the meantime if you want to make progress with this model, you can replace that surface (and it looks like the equivalent one on the back too) with the attached version which will mesh properly.

- Michael

Well, it wasn't easy but this meshing bug is now fixed for the next beta.

- Michael

Thanks! :)