How to Make a Roman Ballista

Cut a 2 foot length of 2-by-4 lumber. Lay it on its 2-inch-wide side. Cut four 1 foot lengths of 2-by-4 lumber. Lay them on their 2 inch wide sides. Position them perpendicular to the 2-foot-long length with their 2-inch-by-4-inch faces flush with the 4-inch-by-2-foot face. Position one at each end of the 2-foot piece, one 10 inches from one end and one 10 inches from the other.

Cut another 2-foot section of 2-by-4 lumber. Lay it on its 2-inch-by-2-foot face. Lay it parallel with the first 2-foot length of lumber. Place it it is flush with all the exposed, 2-inch-by-4-inch faces of the 1-foot long sections. This will form a vertical rectangle with a smaller, horizontal rectangle in its center. Screw the whole thing together with decking screws.

Cut a six-foot length of 2-by-4 lumber. Wedge one end between the central, foot-long lengths of lumber. Press the end of the 4-inch-by-6-foot face flush with 2-foot length. The two 2-inch-by-6-foot faces need to be flush with 1-foot lengths on each side. Screw in place with decking screws.

Drill an inch-wide hole 8 inches from the end of one of the 2-foot lengths of lumber. Drill another hole 8 inches from the other end. Drill two more holes in the same places in the other 2-foot length. You should have two pairs of holes opposite each other.

Lay a hardwood rod over the top of one of the holes and under the hole opposite it. Loop the string over the rod, bring it down through the hole, out through the hole on the other side and over the rod that covers it. Cut a further length of rod about 3-feet long. Push one end through the middle of the loop you have formed.

Continue looping the string around the rods. Use as much string as you can fit through the holes. When you are finished tie the two ends very securely together. Screw four decking screws into the outer face of the rectangle. Put two near the hole in the bottom of the rectangle and two near the hole in the. Position them about 3 inches from opposite sides of the hole. Leave about 2 inches of each screw standing out from the wood.

Repeat the process of wrapping the string through the holes for the other pair of holes. You should now have something that looks roughly like the firing end of a ballista but the limbs will be hanging loosely because the string is not yet coiled. Turn the rods on the top and bottom outwards to coil the rope. Twist the rods on the left side clockwise and the rods on the right counterclockwise.

Continue doing this until the rope is coiled really tight. Secure the rods against the screws in the top and bottom of the box. The tension will keep them held in place. Drill a hole in the outer end of each limb and tie paracord between them.

Chisel a grove into the center of the 6-foot plank. Sand it's edges smooth. Lay further plank across the handles of the wheelbarrow and tie in place. Screw the box to this plank to give your ballista mobility.