Thanks RichardPhat, both your posts were very helpful. To answer your question, I didn't mind the proprietary filament TOO much, but the real issue is that despite my efforts, my printer has stopped correctly reading models and will fail at the sizes of the model, sometimes doubling two instances of the model on top of eachother, and the small print bed. The makerbot 5th gen does have proprietary filament, but you can use external if you either create a slight mod or just wrap the external filament around the makerbot spool. I'll update the post soon with more requirements, and take a look at what you've suggested.