How to Make an Office Trebuchet (catapult)

I know it has been over a month since I updated, but that's because I've been extremely busy making projects.  I would try something, and it would fail.  I would make something else, and it would fail.  Finally I made a project that is worth presenting to an audience.

Think you need more firepower than a wimpy pen gun?  I've got a solution called the Office Trebuchet.  In case you don't know what a trebuchet is, I'll give a short explanation.  A trebuchet is a catapult that uses a heavy counter-weight on one end of the catapult to send the projectiles on other side of the catapult flying.  Here's a picture.

It looks as if that trebuchet is built of some sort of plastic that looks like Legos.  I will be building mine out of pencils and a few other materials.  Now without further ado, let's begin.

And please don't comment on the strange looking pencils.  They were the only ones I could find that were completely useless.  Remember, by using used up material, you are recycling!

Tools of the Trade:
6 pencils of the same size
2 pencils of the same size, but smaller than the other 6
9V batteries, or a bunch of AA's
Duct tape
Fishing line, or string
Cardboard

Step 1: Forming the Cross-pieces
Take two pencils and lay one on top of the other, like so.  Use duct tape to secure them in place.

 Repeat.

Now, take the fifth pencil and put it in between the intersection of the two pencils, where the duct tape is.

Repeat with the other side of the pencil and the other two pencils. 

When done properly, the structure should look like the frame of a swing set, standing up.

Step 2: Reinforcements
Now you will notice that the frame is slightly wobbly.  That's not good, especially if you are sieging a nearby office cubicle.  Take one of the shorter pencils and tape it onto the bottom of the frame, as shown in the picture.

Repeat with the other side.

Your catapult frame should look like this:

Next, tape the four legs onto a piece of cardboard.

Step 3: The Swinging Arm
Take a length of fishing line and create a circle.  Tie off the ends.  Take that circle and wrap it around the middle beam of the catapult.  If you need help, refer to the picture.  That's what it's there for.

 Next, slip a pencil in between the "V" formed in the picture and the pencil.

Tape the fishing line onto the pencil arm to secure it.  It should be tight enough that the arm doesn't slide around the middle beam, but loose enough that it will easily swing.

Step 4: The Counter-weight
This step requires the 3 9V batteries.  Tape them together as shown in the picture.  You should use duct tape, as they are quite heavy.

Next, tie the fishing line around the block and secure it with tape.

Finally, tie the fishing line around the shorter end of the swinging arm.  You may want to cut a notch in the pencil first to make sure it doesn't fall off.  Go the extra step and hot glue the line onto the notch.  Tape it as well.

If you want to give this more firepower, add more weight with more batteries.  But for now, this is all that is necessary. Next thing to do is add a fork or spoon onto the other end of the arm.  You are done!  Trebuchet complete!