Rabidgremlin's
Soapbox

My eldest (currently 5) is big on “making” inventions” and experiments. Last weekend he desperately wanted to invent something with engines. Not having any engines handy I figured we could perhaps do something with elastic bands. Googling didn’t turn up anything too exciting but I did come across a picture of something from my childhood: a cotton reel with and elastic band threaded through the middle of the reel and held in place with a matchstick which you then wind to make a wind up toy:

Source http://www.minieco.co.uk/cotton-reel-tanks/

Unfortunately I didn’t have a cotton reel (nor suitable elastic bands it turns out) but after raiding the recycling bin and craft supplies I managed to collect:

• Some cardboard toilet rolls
• A pizza box lid
• Some elastic bands
• Some popsicle sticks
• Some small matchstick sized bits of wood

First off I got the boys (child number 2 now joining in) to trace out 4 circles on the pizza box lid, using an upside down glass as a template.

These we then cut out as wheels, punching a hole in the middle of each one.

We then threaded an elastic band through the wheel, down the cardboard toilet roll and through the other wheel. On one end we hooked the elastic band over the matchstick sized bit of wood and the other end went over the tip of the popsicle stick.

All set we wound up the elastic band (using the popsicle stick) and calamity! The elastic bands we had were too weak and snapped when wound up :(

A quick raid of the bathroom secured us a couple of hair ties as replacements for the elastic bands. Unfortunately these were too strong, when wound up nothing moved… so off to the garage where we found a couple of metal washers to insert between the wheel and popsicle stick and…. success!

After some experimentation we discovered that its best to not wind the contraption too much, otherwise it just goes into a crazy spin! However if you wind it up about 7 times it travels in a nice straight line.

We taped the wheels to the cardboard tube with some sticky tape and the boys then decorated their vehicles with paint and pens. Then it was off to the driveway to hold some races ☺

Here is a video clip of the vehicle in action: