1. Ballista Project 2 120mm Axle hole 3 Nails 1 200mm
You will need to make two of these structures, exactly the same dimensions – this is so they will both fit together.
First smooth the wood down using sand paper and files.
Drill a hole in piece 2 approx 50mm from the base – this is for the dowel rod
Attach piece 1 to piece 2 using one nail. Then after cutting the sides to a 45 degree angle attach piece 3 to piece 1 – then attach the top to the rear of piece 2.

2. Ballista Project
Using the remaining 4 pieces of wood, attach them as shown to the other structure. Your ballista should resemble the image above.
Attach the wood using glue, nails, and screws if need be.

3. Ballista Project Ping pong ball housing Drilled hole for dowel rod
Hook
Place the metal hook about 60mm from the end of the wooden rod – this will house the elastic on your ballista
Drill a hole for the dowel rod to go through about 10mm from the bottom of the wooden rod.
Come up with a housing for the ping pong ball to go above the hook. This can be made out of cardboard or wood.

4. Ballista Project Slide the dowel rod through piece of wood 2.
Slide the Ballista arm onto the dowel rod so that it sits in the middle
Slide the dowel rod through the opposite hole
The arm should be moving freely, with NO obstructions. If this is not the case then you will need to take a rounded file and file the hole until it becomes slightly bigger.
If the arm does not move freely, there will be no power in your ballista

5. Ballista Project
Hook needs to be placed in the centre of the front block
Put the other hook on the front of the catapult. The arrow shows where to put it. Then run a rubber band from that hook to the hook on the catapult arm. If you don't have a rubber band that is long enough you can tie multiple rubber bands together . Experiment with the length so you get some good spring action

6. Ballista Project
You will need to decorate your ballista in your teams colours. You will each have an attempt at firing it into the target – but ONLY 2 attempts each

7. Ballista Project