Visual markers are graphic symbols designed to be easily recognised by machines. They are traditionally used to,track goods, but there is increasing interest in their application to mobile HCI. By scanning a visual marker through a camera phone, users can retrieve localised information and access mobile services. One missed opportunity in current visual marker systems is that the markers themselves cannot be visually designed; they are not expressive to humans, and thus fail to convey information before being scanned. This paper provides an overview of d-touch, an open source system that allows users to create their own markers, and control their aesthetic qualities. The system runs in real-time on mobile phones and desktop computers. To increase computational efficiency, d-touch imposes constraints on the design of the markers in terms of the relationship of dark and light regions in the symbols. We report a user study in which pairs of novice users generated between 3 and 27 valid and expressive markers within one hour of being introduced to the system, demonstrating its flexibility and ease of use.