Of course you know, this means war!
Load this miniature rubber-band powered crossbow with a cotton-swab "bolt", and try your skill in marksmanship at distances up to 10 feet!
Others have done this before (e.g. http://www.thingiverse.com/thing:509659), but of course I couldn't resist designing my own. This design is simplified from some of the other miniature crossbows you may find. It uses no non-printed parts, save for the rubber band and cotton swabs. You you can omit the "clip" part for a functional design that prints in one piece. If used, the clip helps to retain and align the bolt with the rubber band, improving function and reliability.
The "Clip" part may be omitted, though the crossbow is easier to use with it. It is printed separately and glued in place. When gluing, place a cotton swab in the crossbow to act as a spacer to support the clip in the proper alignment.
The crossbow is designed for a lightweight rubber band, about 1.5mm thick.
Cotton-swab "bolts" are made by clipping one cotton ball off of a two-ended swab.
Please use safely, at your own risk. Do not give to children or adults. Do not point the loaded crossbow at anyone or anything. Do not assume that a cotton swab is a "safe" projectile. Wear eye protection. In short, maybe just forget about this and go read a book.