The results are in! My truss project full of triangles was able to hold a lot of books. It held nearly 10 medium-size books. I knew that the strongest shape is a triangle so I added the supports to be all triangles to make sure that it held up nicely.  I also built a catapult. The catapult is made out of popsicle sticks, rubberbands, and a bottle cap. It does not matter where you put the bottle cap on the first half of the slanted popsicle stick because it will go the same distance. It also barely matters, if at all how much you push the slanted stick back to any angle. Numbers: From the effort arm tip to the fulcrum(the bottom) is 150mm. The Load to the fulcrum is 100mm, 150mm/100mm= 1.5 mechanical advantage. The catapult can hit about 3 ft long and a couple feet high and can fit up to about 3-5 marbles depending on positioning.