Badass LEGO Guns: Building Instructions for Five Working Guns by Martin Hudepohl is a pretty cool book. Using parts you’ll most likely have to custom order along with rubberbands and super glue, you can build any of five guns, from the semi-auto “Parabella” pistol to the fully automatic bullpup “Warbeast”, as seen on the cover. There’s also a neat butterfly knife called the “Magic Moth” available as well. If you have a bit of spare time, patience, and a love of LEGOs, then this might just be the next set of projects you could be looking for.