This is the trebuchet my father-in-law and I made for my son.

The throwing arm separated from the rest of the trebuchet.

Two ounce fishing weights provided the ballast. There are a total of ten of them for 1 pound, 4 ounces of ballast.

The pivot point of the throwing arm.

This is where the sling attaches to the throwing arm. One end is fixed, the other slides off the pin to release the projectile.

A close-up of the yoke in which the throwing arm rides.

The brace that holds the yoke to the support arms.

Front view without the throwing arm.

Side view without the throwing arm.

Top view without the throwing arm.

Bottom view.

The throwing arm resting in the yokes.

The basket that holds the projectile.

The projectile of choice for my children.

Cocked and ready to go. The yardstick is serving as a trigger.

The sling laid out in the raceway, ready to fire.

The ballast end of the throwing arm, ready to fire.