STEM Building Challenge for Kids: LEGO Duplo and Pool Noodle Marble Run - Frugal Fun For Boys and Girls STEM Building Challenge for Kids: Create a LEGO Duplo Marble Run! Pool noodles plus LEGO supports make a great engineering project for kids. Stem Projects, Lego Projects, Projects For Kids, Preschool Projects, Lego Duplo, Lego For Kids, Science For Kids, Blocks For Kids, Stem For Kids