I've been working on my latest layout and found a tool that makes cutting bass wood or even kit bashing a styrene plastic structure quick and easy. After cutting windows or door frames from existing styrene plastic structures, you'll need to trim the excess with a utility knife or exacto knife.
I don't know if this tool was ever mentioned here. The tool I use is a Craftsman Edge Utility Cutter. This cutter uses utility knife blades and are easy to purchase at any hardware store.