When originally printed, there was a lot of support material holding up the lip of the open lid. It was too thick to just snap off, so I borrowed a friend's Dremel tool to take it off.
In this photo you can see I got a little too aggressive and sanded off some of the material that was supposed to be there (bottom right). I also tried some fine sand paper to see if I could smooth out some of the banding from the print; this caused the ugly marks you see below. According to a site I found, this is one of the differences between using PLA and ABS filament. The Makerbot uses PLA only. ABS is supposed to be easier to sand, and can also be finished using acetone.