Here is my Grail-o-matic: a customizable design you can use to make vases, cups, chalices, or even Tuscan pillars by rotating a profile you draw about an axis, as if on a lathe. Part of the fun is designing your own Rubin vase illusion. See the faces in the negative space around the default design? You can make faceted columns as well as smoother cylinders by reducing the number of rotation segments. The output is a solid model intended to be printed with no infill and no top layers. (Update: if you include the interior concavity in your cross section drawing, you can print with regular infill etc settings. Here's an example!) Printing Tips Here is a quick screencast showing how to use the polygon sketch control in Customizer to draw a profile for your chalice. Observe how I drag the cursor outside the box to ensure the drawing is flush with the top, bottom, and left edge (which is treated as the lathe axis by default). http://www.youtube.com/watch?v=1kMebhH0xIM It is quite possible to make designs that are difficult to print without supports or infill, if at all. Pay careful attention to the slope of the lines you draw - steep horizontal overhangs will be trouble. For example, see the attached close-up. The overhangs in the design are translucent in my test print, and unfortunately somewhat porous (the rest of the print holds water). Part of my Customizable Containers series.I printed the pictured test copy of the default design in brown PLA on my Printrbot Simple at 0.8 scale. 0.1 layer height; 4 perimeters; 0 infill; 0 top layers; 13 bottom layers. As noted in the Printing Tips section of the description, it's watertight except for the steepest parts of the design, which came out a bit porous.