Icons have become an inseparable part of Graphical User Interfaces. There is well-developed literature describing novel applications of icons and methods for evaluating existing icons. However, there has been comparatively little research into the processes necessary to design effective new icons. This paper will introduce a novel design methodology for developing graphical interface components, including icons, called Presentation Discovery. The method is grounded in Semiotics and Personal Construct Theory, and adapts Knowledge Acquisition approaches to the graphical domain. A pilot study applying Presentation Discovery in a biomedical domain is presented.