I'm getting ready to pull the injector pump off my "junk" engine, and put it into storage should anything happen to my current one. I wanted to seal off the various ports and decided this was a suitable application for the printer. I took some measurements and designed some plugs and rings in Sketchup and printed them out - injector line fittings, fuel intake, fuel supply and fuel return. Turned out pretty decent.
Obviously could have used lots of different ways to do it, but the printer worked out nice.