"The pen is mightier than the sword" -Edward Bulwer-Lytton
This is never truer than when it is fired at high velocity from a paper crossbow.
Office-wars will never be the same again.
Step 1: You Will Need
9 sheets of A4 paper
2 pens (BIC type)
Some string or wire
2 binder clips
A sharp knife or scissors
Step 2: The Arms
Take 4 sheets of paper and fold them in half long ways.
Use your knife to cut the sheets along the score line.
Roll each paper stack around a pen until it forms a tube and secure it with duct tape.
Remove the refills from the inside of your pens and insert them into the ends of the tubes.
The image shows them taped in but I changed my mind after I took the photos and found a better solution for a later step so don't tape them just yet.
Fold the tube in half using the pen body as a lever. It is important that both sides are even.
Step 3: Assembly
Stack 5 sheets of paper and roll them along the long axis, secure with plenty of tape as this piece will come under strain.
Attach the two arms (one at a time is easier) with plenty of tape, don't be shy here!!!
Step 4: Bow String
I used some 2.5sq electrical cable for my bow string, you could use string or paracord.
This is where I decided that taping the pen bodies in was not the best idea. I was going to tie loops and fix them to the ends of the pens. However I found it better to tie a knot in the cable and slide it into the pen until it became trapped at the narrow end. I then reinserted the pen body. I trimmed the string about 20mm longer than the space to the other pen tip.
I removed the second pen body, inserted the string until it came out the back end, tied a know and pulled it back in, I then (with difficulty) reinserted the pen to the arm and taped both in place.
Step 5: Guides
Use the 2 binder clips as guides for the bolt (arrow).
The one in the middle should have the arms up to stop side slippage and the one at the back should have the arms down to act as a grip.
Step 6: Prepare the Bolt
Take a pen or pencil and create a small notch in the back end, this will give the string somewhere to sit and stop the boot jumping the string when firing.
Step 7: Have Shooty Fun
Put the string into the notch and pull back to the end of the crossbow.
Use your thumb over the top to hold the bolt back until you are ready to release and fire.
Just a safety note here: This instructable creates a projectile weapon, despite its appearance, it fires with considerable speed and force, please do not shoot it at people, animals or expensive things as it will cause harm.