YES IT'S NOT A SOLID, ENCLOSED OBJECT. THIS IS ON PURPOSE! :)
A "Pencil Pot" I made when I was inspired by the creations I saw on the #WaveyWednesday Twitter hashtag.
SPECIAL SETTINGS! Print 0 top layers! Otherwise it'll try and give it a lid, and we don't want that. I printed at 0.8mm wall thickness, and the result was translucent almost, despite being a solid white PLA, so you might want to thicken the walls up a bit. And yes, I did try Surface Only mode, and that cut the bottom off.
Using a 3D modelling program I drew a spline for the rim, then swept that along a straight line. I adjusted the scale and rotation of the sweep operation until I was happy with it, then exported.