I’d be very careful if the client asks for 3d/CAD files.
I had some trouble with such clients, i _never_ agree to give away the 3d model, unless the client is someone I know, and I’m exactly sure what he is going to do with it.
When you provide images or animations, there is no catch.
When clients want CAD files, they often expect that they can just load it into autocad and render out images, looking the same way as those you rendered for them.
Clients also believe that they can convert the CAD file into some VRML format, and do interactive presentations, again with the same appearance like the stills you rendered for them.
Even if the person you are dealing with, understands that it’s impossible, to give them your complete scene files, because it only works with 3dsmax, you can’t share the textures, it only renders with VRay, plugins, etc,
there still may be some other person/manager who expect ridiculous things, based on the agreement to provide them 3d data.
Even if they understand that it’s going to be a raw autocad DWG only, with raw geometry, no textures, no lights, they will still bug you, because the file isn’t organized in layers, as they expect. Or they will bug you, because the person who edits the file can’t figure out the scale, or doesn’t know how to load it into sketchup.
In my experience it’s important to memorize that NEW CLIENTS = stupid and/or annoying. The exception proves the rule.