Attached Link: http://www.iaw.on.ca/~jspirko/models.htm

You can however download other folk's primitives for Bryce and, providing it's acceptable, make a model and export that. It depends on the terms of use, just have to read the readme's and see which allow redistribution and/or commercial use. I'm fairly sure I saw some here in the Bryce freestuff, you can also find some presets at the link I've posted. Follow the "presets" link at the top on that page. I'm not sure about the usage restrictions though, the readme's are vague about it.