Hi Involute, yup you would use STL format for sending your model to Shapeways or Ponoko for 3D Printing.
You've also got to make sure your object is a completely closed solid, you can't have just surfaces that don't enclose a volume.
When you select an object there is a type indicator in the upper-right area of the window that shows the properties for the current object, that should read "solid", if it just says "surface" or "joined surface" that means your object is not fully closed and you still have some openings in its skin.
> Do you know of other users' experience with this workflow
> (MoI -> 3D printing service)?
Yeah, there have been quite a few people using MoI for that.
