OK, thanks for the suggestion. I'm currently investigating 3DS format. It seems that Autocad does not document it, and any 3DS format documentation is done by individuals. If anyone has a good source for the format, please let me know.

Thanks for the input. All good suggestions. Right now, I have a simple prototype that allows you to create cubes and rudimentary windows of different sizes, move them around, position them, pan and zoom the camera in 3D space, add texture and colors, and other simple stuff like that. The other major stuff I need to add is more objects (roofs, doors, trim, some of the suggested items here, such as domes, etc), more operations (scale, make a grid of objects, say windows, etc), and save/load. The program will externalize certain elements such as color definitions, textures, and objects. That way, it can be extended without changes to the program for adding new elements. You could add textures by specifying their name and file location, etc. Objects would require the definition of the objects attributes (e.g. depth, width, height for a simple cube object) and some formula/instructions for rendering from those attributes (through a descriptive language). Obviously, this is a lot of work, so I'm starting small with some fixed elements (cubes, windows, simple roofs, simple doors, etc). Early versions will probably not create impressive structures; at some point the productivity of this tool will surpass the productivity of doing the same thing in your favorite editor. The real gains come, I would think, from alignment/construction operations that are tedious in a 'generic' graphics editor (e.g. a hexigonal building). One major question is the file format. I was thinking of saving to .X file, because I can find documentation on the format, and it seems to be able to save the 'extra' information I need to maintain my 'special' objects. The problem I see with a lot of formats is that they don't seem to be able to save and maintain this 'extra' information so that the model could be re-imported into my tool after being editted by your favorite tool. Could be that my tool would have to simply be happy being a 'rough' construction tool that takes the model to a certain point where your tool takes over. Please post any suggestions; I would be grateful for any input. I will post progress, and can/will reply to any email inquiries (although having a community forum reduces duplicate posting effort). Thanks again. Kevin