After building a doll house and disk drop board, my daughter had another idea for a cardboard project. This time she wanted to build a rolling ball machine. Again, as usual, I comply. I had no idea of what she had in mind. So I asked her to do a drawing and explain how the machine is supposed to work. She drew a spiral on paper, cut it out along the pencil drawing. Then, pointing at the dangling spiral, she said "that is what I want".
She explained to me that the balls will roll from the top and spiral down. Not knowing what she is imagining, I prodded her further. Then she explained that we need to build walls along the spiral to keep the balls from falling off. If you are finding it difficult to understand, welcome to my world with a 7 year old :).
The design reproduced on cardboard
Instead of trying to figure out her thought process, I decided to just play along. I copied over the drawing from paper on to a cardboard. This is what I was left with after cutting the spiral.
Next, she wanted walls around the spiral. So we cut lots of cardboard into stripes and started building the walls.
Eventually I built the walls all around with hot glue and clipping separate stripes together with stapler. Then my daughter tells me that we need a pillar in the middle to make the center higher then the rest so the balls can roll. Ah! That is the missing piece of puzzle. Her grandfather rolled up some cardboard and made a pillar out of it. Glued it in the center.
We realized that the spiral is not stable. So added a few more pillars. The machine is ready for play. She had a lot of fun playing with it. Watch the construction process and the fun she had in the video below.