CYCAS is a new 2D + 3D CAD software, based on GTK. In addition
to typical CAD functions, it offers special elements and techniques
for architectural design. The 3D data can be exported e.g. to
POVRay(TM), so you can arrange quickly a presentation of your
design. The full version of CYCAS will be released soon. A stable
preview version for Linux/x86 is free to download.