A 3D drawing methodology based on voxel-graphics was applied to the design of multi-component engineering systems, such as fuel-cells. Using this methodology and Java-technology a graphics user interface (GUI) for a fuel-cell simulator program was developed and used in simulations of large fuel-cell stacks. The GUI is capable to setup, run and monitor simulations remotely from a web-browser. The geometric design module was implemented using 3D voxel sculpting methodology and data visualization, which is prototyped after 2D pixel graphics systems. The developed approach was primarily aimed at the design of complex multi-component engineering systems. However, the flexibility of voxel-based geometry representation enables one to use this technique for both 3D geometric design and visualization of unstructured volume data. Examples of both applications are presented, with the focus on fuel-cell stack simulations. (C) 2004 Elsevier B.V. All rights reserved.