Rutherford scattering toy, and more

My friend Konrad showed me this awesome toy he made.

I know it doesn't make sense yet, so let me explain. Basically, you take this marble and roll it down the tray through the pegs. The pegs sort of randomize where the marble rolls through the hidden section. Inside the hidden section, it looks like this:

The object of this toy is to find the cross-sectional area of the rings. Konrad said he built this based off of a toy he was given in middle school. He wasn't told how to do it, just to do it. Maybe I shouldn't say anymore about that toy except that it is awesome. No instructions, just figure it out. Oh, I can say one more thing, he said that you can take the rings out and measure them if you want to check your answer. Also, you can put in different sized rings if you like.

After discussing this toy, Konrad told me two other cool things he did in middle school. One day, his teacher showed the class an old-school pocket watch. He then told the class to come up with a list of 50 ways that you could make the watch run slower. That seems pretty tough, I imagine I could come up with at least 10.

This same teacher also gave students different sealed boxes with something in it. The goal was to determine what was inside. Konrad said his had a pencil. He figured this out by counting the clicks as it rolled inside the box. He also could estimate the length by sliding it in the same direction as the pencil was pointing (until it hit the wall). A different student had sugar in his box. Another student had something (he didn't say what), but his father worked in the medical field. To determine what was in the box, he took it to work and x-rayed it.