My son has always been fascinated by how things work, so I knew I had to try out this cardboard automaton with him. I love that it's a fun way for him to play with simple machines; and it also creates a really cool art piece!
How We Did It
The first step is to cut the top off the box. Since I had this extra piece of cardboard from the top of the box, I decided that was the easiest way to create the cams (the spinning circle pieces).
I traced around a drinking glass, and then cut out 4 cardboard circles. Then I glued two of the circles together to create a thicker cam -- this helps make the connection between the two cams work better. You could use tape, school glue, or hot glue for this.
Next, the axle! I took one of my double-thickness cams and poked a skewer into the center (don't worry if it's not quite perfectly centered, it'll still work). I used hot glue to attach the skewer, but you could also use kid-friendly school glue or even tape.
Next step is positioning the skewer/axle in the box. With the end of my scissors, I poked a hole about an inch in from the top edge of my box. Then I cut my straw in thirds and poked it through the hole. (You can optionally reinforce the straw with a drop of glue, but it'll stay put without it.) The straw allows the skewer/axle to spin freely.
Now for the second cam and the linkage where the two cams meet. I poked a second skewer through the center of the second cam, and then poked two more straw holes through the sides of the my box. The two cams meet at a right angle.
The only trick here is to make sure the cams don't touch the back side of the box. If they do, you can either move the skewers, or you could cut out a window in the back of the box so the cams spin freely.
With the cams in place, I had my son help me test out the motion; he was delighted to discover that rotating the horizontal skewer turned both cams, which rotated the vertical skewer
For a slightly better connection between the cams, you can hot-glue a rubber band around the edge of the bottom cam, but we discovered ours worked just fine without it.
To make turning our automaton a little easier, I finished it off by hot-gluing a little cardboard handle to the horizontal skewer. This is entirely optional, and definitely a grown-up step!
Now for the best part -- adding the decorations! My son decided to draw some good guys and a bad guy for our automaton, which I helped tape onto pieces of black card stock. Just for fun we wrapped a pipe cleaner around the top of the skewer, and then added a little pom-pom monster with eyes. As the handle turns, our good guys and bad guys chase each other around the skewer, while the pom-pom monster bounces up and down. So fun!