you can export terrains (fully-shaded) and imported meshes ONLY. You cannot export cubes, spheres, other primitives, rocks, or any booleanized object. To export a terrain, create your terrain, go to the Terrain Editor room, and RTFM. To export a mesh which was previously imported (exactly why you'd want to do this, I'm not sure), Edit the mesh, and then in that dialog box, hit control-D, and you'll be presented with a save as... box. (this is a hidden item that isn't in the manual). You can save a Bryce object as a 'preset', in Bryce-proprietary .obp format. To do this, select your object, click the little triangle next to the "create" palette tab, let the image render, and hit "add". RTFM for details. These presets, however, can NOT be imported by other programs, because .obp is a custom format.