Towards a marketplace of visual elements for notation design

New visual languages and extensions of existing notations are increasingly introduced for various purposes. There are many frameworks and theories that aid designers in creating cognitively effective visual notations. They usually provide general guidelines, which are not easily operationalized without extensive user involvement. However, often such user involvement is difficult to achieve, especially in scientific settings where finding enough participants with the needed background knowledge is far from trivial. In this paper we propose the idea of creating a searchable marketplace of visual elements, in which designers could share and exchange elements of visual notations. A key feature of such marketplace would be the ability to certify such elements via procedures grounded in empirical research. We discuss a proposed structure of the marketplace, and the challenge that the need for certification poses to its design.