I see possibility to upgrade the technology to draw on various tubular shapes (like pipes), combine them with 3d printers to add decoration or replace the painting top with mill or laser cutter.
This segment of small DIY CNC devices will certanly expand in the future ...
The Mug Maker
http://www.evilmadscientist.com/2013/mug-marker/
Mug Plotter
Complete and detailed building instructions fro Mug Plotter: