I’ve always wanted to try making a double-walled teacup, but the complicated and technically tricky assembly always made me pause. The concept of a double-walled cup is to insulate your hand from the interior temperature of the vessel. For mugs or glasses, it can also be used as insulation to help keep your drink warm. For a small teacup, that’s not really the concern, since you’ll probably drink the small amounts of tea or espresso before the liquid would cool down. Really, it’s just a different, interesting way of making a handle. Since you have two walls, it is possible to cut away part of the outer wall to create a decorative effect. My concept was to cut significant portions away from the exterior to make a simple, bold, linear pattern. I thought that this sort of delicate line work would give a unique effect (and one that would be incredibly difficult to achieve if you were building this by hand.) I settled on a simple chevron pattern radiating around the edge of the cup. This way as much as half of the exterior wall might be removed, leaving a network of legs to support the cup.
Whatever concept you have for your vessel, I'd encourage you to dig into the details. The shape, size, and weight of your container will all contribute to it's functionality (not to mention how it looks.) The more unconventional your design is, the more likely that it will be tricky to print or get to function properly. I certainly wouldn't discourage designers with crazy concepts, but you just might have to do a little more homework to get everything in line.