This is a cup made in the opensource software called Blender (Version 2.72). I was trying to make a simple object, and here it is! The previews aren't real, they are artist's (yeah, right) renditions of what it would look like. (Rendered in Blender Cycles Renderer, Composited in Blender). I have never tested this in a 3D Printer, so PLEASE (with a cherry on top) print this model and then post the results!

This is how I made this object in Blender 2.72:

1. I added a circle, but set the vertices to 8 so that it would be an octagon.
2. I extruded the octagon outward, so that it had thickness.
3. I extruded the whole object upward, then rotated the top faces on the Z axis.
4. I extruded the top, then rotated the new top on the Z, then repeated again and again 'til I got to a good height.
5. I added a face to the bottom so that the cup would have a bottom.
6. I uploaded it to thingiverse.