Here's the project: You have a 60x60x60cm box, and a marble (the material of the marble could be steel, glass, plastic, etc.). There are 2 holes in the side(s) of the box that are 20cm vertically apart. The marble must start from the lower hole with basically no velocity, and by any non-electrical means shoot out of the upper hole. How would you do it? What kind of simple machines / devices would you use to propel the marble? I am doing this myself, but I am really interested in seeing what some people will come up with!