I know this might show my drastic ignorance on the subject, but does AutoCAD allow for object "instances"? That is, instead of copy/paste and increasing your object count, you would have a single object, instantiated in multiple locations - that way, you would only have multiple "pointers" to a single point in memory for multiple repeating objects (corridor segments, transporter rooms, crew quarters, etc.), taking significantly less RAM. It's a pretty common programming concept, particularly in the object-oriented world, but I was curious if AutoCAD had a similar feature to help cut down the size of runaway files like this one. Just a thought. You can tell me to shut up if I'm talking out my ass on this one.