Step 1: Parts List

So short, I almost didn't make one. This does not include ammo (1+ dark grey connectors).
If you do not use all of the parts when building, you probably did something wrong.

5x dark grey
1x green
12x purple
1x white
4x orange

2x green
7x white
8x blue
3x yellow

2x blue spacers
1+ elastics

Step 2: The Frame

1. Make these.
2. Make these.
4. Put them together.
5. Add a yellow rod as shown.

Step 3: The Throwing Arm

Picture of The Throwing Arm
1. Make these.
2. Put them together like this.
3. Make these.
4. Put all parts together.

Step 5: Loading & Firing

Picture of Loading & Firing
To fire the catapult, you need one dark grey connector.

1. Hold catapult by the base as shown (the picture does not have elastics, but yours should).
2. Put ammo on as shown.
3. Hold ammo and pull back as far as the yellow rod.
4. Let go. 
5. Watch a small piece of plastic fly across the room and hit your teacher in the face. Say someone else did it.

That's it!

Note: Step 5 is optional, but extremely funny.
bobsley1231 year ago
You can make this the ammo
13, 11:25 AM.jpg
zazenergy4 years ago
Looks like fun!
^ agreed
SN1P3RL0RD2 years ago
Its powerful for its size and accurate. Can you make one for grenades?
~KGB~4 years ago
well its ok