I was bored on a Saturday afternoon and with an engineer friend. We decided to have a contest to see who could design and build the best printable bow and arrow, using the following constraints:
One 100mm x 100mm panel of parts
No more than 2 rubber bands
"Reasonable" print time (under 1.5 hours)
"Reasonable" design time (under 1.5 hours)
This was the my entry. The picture is of the first revision, which had a few issues (pins were too small to print cleanly, holes were not oversized enough, pins would shear). The uploaded file is the second revision, which has not yet been tested but should address all of these issues (my printer is down today with "null version reported" so I'll try to get it tested ASAP).
Print the plate, clean the parts up (the holes in particular).
Slide the two leafs over the center piece and put the retainer plate on the back.
Heat up a knife blade (I used a lighter) and press down on the tabs to "fuse" them in place.
Take a piece of hot filament and slide it into the hole on the center piece of the bow; this is now your guide.
Slip your end cap over the filament and mushroom the tip again with a hot knife to keep you from loosing the cap when launching pencils.
Finally, take a rubber band (you'll need a fairly long one) and stretch it across the nubs at the ends of the leaves.
Load a pencil, draw back, and fire!