For my dynamics course at the University of Prince Edward Island, my professor gave the class the task of designing and building a device that can be used in snowball fight. The device could be either a defensive or offensive device or both. My partner and I took the offensive approach and began to ideate for some designs. After a lot of thinking we came up with the design of a snowball launching catapult. In this instruct-able i will be explaining how to build this device as well as how to use it in a snowball fight.

Step 1: Materials and Tools Required:

Materials:

7ft piece of 2"x4"
8ft piece of 1"x2"
Sheet of plywood (minimum 35"x20")
Copper pipe
3 eye hooks
Box of 2-1/2" wood screws
Small metal bracket
6 - 2" nails
Bungee cords

Tools:

Impact drill
Jig saw
Measuring tape
Vice grips
Hammer
Drill press
5/8" spade bit
Framing square

Step 2: Material Preparation

Before beginning the assembly, it is best to get all of the materials ready for building. This will provide a faster build as well as a more organized and straight d=forward assembly.

Cut the 2x4's in to 17" pieces, cutting one end of each with a 45 degree angle.
Line two of the 17" piece on top of one another, using the spade bit, drill a hole approximately 1" down from the flat edge in the center.
Cut out an 11" piece of 2x4.
Using the jig saw notch out a 2"x1" rectangle in the center of the 11" piece as seen above.
Using the miter saw cut a 3ft piece of the 2"x1" wood.
Using the spade bit again and the drill press, drill a hole 1ft up from the end of the 3ft piece.
Cut out two 2ft pieces with the 2"x1" lumber, cutting one end of each at a 45 degree angle.
Cut the plywood to dimensions stated in the materials list.

Step 3: Assembling the Frame

Line two of the 17" 2x4's up with there holes, use the copper pipe as seen above.
Using the wood screws and impact drill, secure them together as shown.
Repeat steps 1 and 2 with the other 2 pieces as well.
Connect the frames to the ply wood base with screws as well from the bottom of the base, leaving approximately 11 inches between each frame.

Step 4: Attaching Catapult Arm and Stabalizers

Attach the 11" piece previously cut between the two frames using wood screws with the notch facing upwards.
Place the two stabilizers (2ft pieces) and line them up with the holes in the frame and mark where to drill the holes for them. Also mark where to cut out notches so that the stabilizers fit snug around the cross member.
Cut out the notches marked with the jig saw, and drill out the holes for the copper pipe as well.
Insert the copper pipe though one frame and as it slides through put one stabilizer on, then the catapult arm and then the others stabilizer. Slide the copper pipe all the way through the other frame.
Screw the stabilizers to the cross member as well as the base.

Step 5: Attaching Bungee Cords and Snowball Cups

Take two different length bungee cords and attach them to the bottom of the catapult arm with a bracket as shown.
Pull the ends of the cords down to the base until there is a little bit of tension and mark where to put the eye hooks.
Clamps the ends of the bungee cords around the eye hooks and then duck tape around them so that they cannot slip off when the catapult is being used.
Screw two cups to the launching end of the catapult arm as shown above.

Step 6: Adding Shooting Range Adjustments (Optional)

To make your snowball catapult more versatile, you can make it so that you can have multiple different launch ranges. You can do this by adding different places to stop the catapult arm using nails and a small dowel to prevent it from going down any further. measure where launching it from these positions will go and mark the distances down by the nails for future reference.

Step 7: Using the Catapult

Using this device is very easy. Simply place the catapult on a flat surface, aim it in the direction in which you wish to shoot, load the cups up with your snowballs, pull down the launch arm until the tension is pretty high and then release the arm launching the snowballs at your opponents.