While at Gettysburg, make a trip to York, PA and take a factory tour of the Harley-Davidson York Assembly Plant
. It's an easy ride. Just take US-30 east from Gettysburg to York. The plant is just east of the city. After you pass underneath I-83, You're getting close to the plant which will be on your left. It's an interesting tour, even if you're not a Harley-Davidson fanatic.
Be sure to click on my link above and read the dress requirements as this is an industrial tour.