Step 3: Build the tower

Picture of build the tower
the dowel for the tower is half the length of the long members used for the base. in my case, that makes them 6 inches.

i placed the tower dowels 4 inches from the end and put screws up into it from underneath.

the support pieces (that make the triangular shape) are simply paint stirrers that i placed where i wanted them, marked where to cut, then used a set of wire cutters to cut through them to shape. then i put them on using staples. these supports are very important, since they transfer the torque put on the tower dowels by the catapult to the base.

i drilled and screwed screws into the tops of the tower dowels. the tower dowels can be spread apart easily (which helps when installing a new rubber band). that's ok, because the only force applied to the pipe (the rubber band) is orthogonal to the pipe (a 90 degree pull - that is, it pulls away from the pipe - not along its length).

next, i simply held the tower dowels apart and inserted the pipe -- the screws hold it in place. the hot glue gun glue keeps the pipe from wiggling too much, but doesn't secure the pipe.