While looking through the junk shelf, I found a tennis ball and something that looked like a cardboard cylinder cut down the middle. I had no idea what I wanted to make but I decided to use them as my materials.
At first, I thought I could cut make a cardboard box and balance it on the semi-cylinder so my tennis ball can roll down. But after spending 20 minutes making a cardboard box, I found another (already-made) box-like thing. So I replaced my wonky cardboard box with the sponge box. Then I put copper tape around the tennis ball and on the middle of the slope.
Just as I thought I had finished, I started changing the position of the wire. Others working in the same room told me it looked fine but I decided to spend more time on it by taking everything apart and substituted the copper tape on the box with aluminium foil between and on the box. Later, paper tape was applied to create 3 conducting spots on the box. Lastly, after being unsatisfied with the angle of slope over the weekend, I flipped the semi-cylinder and stuck the box on the other side.
And here is a video of the finished product.