A swirly vase that has been described as "beautiful" by all and sundry.
To make a vase, print with several bottom layers, two walls, and no top layer...s.
Blender seemed to have trouble with the STL export of this. As a result, you'll need to scale it up a fair bit in your slicing program. I used Slic3r and from memory it needed 1000% scaling. It printed fine.