My son has to build a bridge for his Geometry class using 250 round toothpicks and Elmers school glue. To get maximum points, it has to hold 86+ lbs. Of course I had to get in on the fun. I've built one, and have two more under construction.
I built a balsa wood bridge for my intro to engineering class for college back in the day, ripped and laminated the balsa back together with super glue. It held over 500# before the cross spars holding the two sides together let go (when they tested it they stupidly looped a chain through instead of having some type of bar to apply a point load). I glued it back together and it lived in the engineering department office for some time. Good luck, those glue joints are what can make it break it!