You should now have a working catapult/crossbow and one piece of ammo to do whatever you wish with it. Have luck and have fun!
Step 4: Adding the projectile guide.
Now you'll need 1(one) of the bamboo skewers. Cut it in half and trim it until it is even (and if you feel necessary also cut off the point). Then glue them to the top side of the main body as wide as your ammo will be.