This should teach your co-workers who's boss. Spend half an hour making it, then have hours of fun hassling your co-workers or target shooting. Mine shot a pencil eraser about 30 feet easily.

Check out Kiteman's version as well. https://www.instructables.com/id/How-to-Make-a-Desktop-Viking-Catapult-with-a-bonu/

Thanks to everyone who voted for me in the Office Supply Contest!

Here's a video of it firing:

Firing.mov
Download

Step 1: What You Need:

- 5 pencils
- 2 pens
- A plastic bottle cap
- At least 14 elastics
- A craft knife or pair of scissors

Step 2: Making the Frame Part 1

- Take three pencils and arrange them in a triangle and use elastics to hold them together. This will be the base
- Use an elastic to attach another two pencils together into a V shape
- Then take the V shape and use elastics to attach the forks to two of the corners of the triangle

Step 3: Making the Frame Part 2

- Place an elastic over one of the arms on the V and pull it through itself (see the first picture)
- Put the pen through the elastic as shown in the second picture
- Pull the elastic tight and wrap it around the pen and frame
- Repeat this for the other side
- Do the same thing with the other end of the pens near the back of the frame

Step 4: The Ammo Pouch

- Use the craft knife to cut a hole in the top of the plastic bottle cap and three in the sides roughly equal distances apart
- Thread elastics through the holes in the sides and pull them through themselves to secure them
- Tie a knot in another elastic and thread it through the hole in the top of the cap, with the knot inside the cap
- Make sure the knot doesn't come through the cap when you pull the elastic

Step 5: Bringing It All Together

- Attach the pouch to the bottom of the frame the same way you attached the elastics to the sides of the bottle cap
- Loop two of the elastics over the pens
- You can repeat these steps to increase power
- To fire place your ammo in the bottle cap and pull back on the elastic protruding from the back of the cap, then release