I recently wanted to make a small trebuchet after seeing some of the bigger ones online. I looked for a kit that includes everything you need to make one, but I quickly figured that I could make a cheaper alternative from scratch. Besides I figured it would be a fun project because I like putting things together. 

I got all of the materials to make my trebuchet from Lowes and it only cost about ten dollars, some stuff I had laying around and a few hours to make. I made it out of three eight foot one by twos, wood glue, finishing nails, and a small metal rod. This was my first trebuchet building experience so for some reason I decided to make a floating arm trebuchet. This design is more complicated than the standard and is more difficult to make because it involves wheels, they help convert the kinetic energy of the falling weights directly in to the object that is being thrown.  This type of trebuchet is the most efficient design.

So I started by making the base. I used my buddies miter saw to cut a base board two foot long. Then I cut two vertical boards eight inches long and glued them on to the ends of the two foot board making sure they are perpendicular to the base, I used the finishing nails to hold the boards together so the glue could dry. Then I cut two more two foot sections, these will be one side of the track where the weight bar will slide. I glued those to the center of the base board making sure to leave a small gap just big enough for the bar to have a little wiggle room and then secured them with the nails. Next, I made the track where the wheels roll. I measured the distance from the eight inch board to the two foot vertical making sure not to overlap on to the track where the bar passes. An identical board should be made for the rest of the track on this side of the frame and both should be glued parallel to and on the same side of the verticals as the base board. The other side is made the same way. For the throwing arm I used another two foot board because I was going for a 2:1 ratio, 8 inches to 16 inches.

Finally, I had to attach wheels and the weights to the throwing arm, but I realized that I didn’t have any wheels or weights. So I made some wheels out of a two by four I had laying around by using a two and a half inch whole saw and a drill press. I used the metal rod I got from Lowes to put the wheels on the arm about nine inches from one side. I used bolt cutters to adjust the length of the rod and cut another piece of rod for the weights. I put this rod on about two inches from the bottom of the arm. The only thing left to do is to put the two sides of the trebuchet together making sure to give the wheels just enough clearance, these pieces can be glued on to the bottom of the trebuchet. Mine ended up being six inches wide. Currently I am holding the two 2 ½lb weights, which I ended up borrowing from my weight bench, and wheels on with hot glue and regular washers, but eventually I will upgrade to lock washers. Any way it turned out pretty good for my first build and it was practically free.