drex, do you know how to make a layer? in your layer manager, you will have a layer named " cad " which you can rename "raw stock", or just leave it cad layer, aslong as you know what it is. copy the part you want as stock on to the empty screen, of the new file. all you should have now is a new file containing the "raw stock" model. now as always, save, and name the file, so you can be sure not to lose it. next, in your layer manager, add a layer, and name in " modified" , then turn the modified layer on, and the raw stock layer off by moving the check mark to modified layer, and clicking the box next to raw stock to turn it off. you should now have a blank screen again. the "raw" layer is hidden, but still there. now copy the "modified " model into the blank layer. you now can toggle between screens and turn each model on or off as needed. I assume your very new to bobcad, to not understand layer management, it might be easier if you just post a file of the models, and ask someone to "show" you how to do it, and then you'll get a little more understanding of it.