The Declarative 3D for the Web initiative by the W3C [W3C 2011] connects 3D content to the Web document, intertwining it with other Web technologies known to millions of Web developers. The goal is to make 3D on the Web more accessible compared to low-level APIs such as WebGL. However, all proposals for Declarative 3D for the Web are missing an essential feature: configurable instances of structured 3D models. While instance mechanisms do exist, they all have limited capabilities to configure instances individually.

In this paper we present a new approach for configurable instances of 3D models that is integrated into XML3D. Our approach comes with a compact interface, a powerful extension mechanism to handle configurations, and an efficient data structures for efficient instancing. We demonstrate how our instance mechanism simplifies the handling of 3D models in several different application areas, including Virtual Worlds, and provide several performance results for the instancing process.