Automaton - cardboard and foam machine

Build a compound machine, that is also an art project, that demonstrates levers, cams, linkages and a chain of forces.
Science content
Physics: Motion and Forces, Newton’s Laws, Gravity (K, 2, 6)
Physics: Simple and complex Machines (5)
  • cardboard boxes to cut up
  • blade or cardboard saw
  • scissors
  • masking tape
  • glue gun
  • sturdy skewers
  • wire cutters, or alternative to cut skewers
  • straw that skewer will fit through
  • washers that fit over the skewer, to add weight, or use modelling clay
  • thick foam sheets, 6mm (about one 9X12" sheet for four students)

Follow instructions from this activity from the Exploratorium, also attached, and summarized below:

In brief:
Make a frame from a cardboard box, with triangles to reinforce inside the corners. Note: do not make the frame too large, or there will be too much play and the cams won't mesh. About 20cm wide and 15cm high works well.
Stick a skewer (a "shaft") horizontally through the frame, adding a circle of foam (a "cam") to it, the placement of the hole in the cam depending on which mechanism(s) you want to make. See the attached file from the Exploratorium for ideas. It is best if the cam is at least 5cm diameter.
Add another foam cam on a vertical shaft through the top of the box that will rest on the first circle. Don't make this skewer too long or it will move sideways. A straw glued into the box to guide the skewer helps keep it upright. Washers, or modelling clay, give some weight to the cam so that it always rests on the lower cam.
Depending on where the horizontal shaft goes through its cam, the upright shaft will move round and round, or round and round and up and down.
Optional: add another circle on the horizontal shaft to make the upright shaft also go back and forth.
Decorate the upright shaft, so that the movement(s) is/are highlighted.


If the box frames are too big, the skewer lengths get too large and there is too much sideways movement.
The Exploratorium new up and down model did not work so well, but check it wasn't because our skewers weren't too long.

Glue gun burn potential means prudent use dependent on the age group and responsibility of kids. If the kids are not mechanically-minded, they will need a lot of individual attention. When an adult has to do all the hot-glueing, some groups get bored waiting around.

Grades taught
Gr 3
Gr 4
Gr 5
Gr 6
Gr 7