This is a neat, and very quick little toy that I first came across on the "Happy Scientist" website.
A couple of minute's work, and you have a toy to keep the kids happy, a fun craft activity, a hook for a fascinating science lesson, and probably the cheapest and quickest at that.
Step 1: Materials and Tools
All you need is a flat, thin piece of wood and something to carve it with.
I have successfully used lollipop sticks, tongue depressors, coffee stirrers and chip forks.
I guess it doesn't have to be wood, but it does need to be fairly rigid.
Step 2: What to Do
The basic poong stick is simple - carve one end to about the thickness of a matchstick.
For your own comfort, carve, scrape or sand the narrow part to a more rounded cross-section. Corners and sharp edges will cut your thumbs or increase the chance of blisters.
You don't have to stick with the plain, er, stick. You can carve and shape to your heart's content.
The basic carving takes only a couple of minutes with a decent sharp knife. I haven't tried, but if you add a sanding bit to your rotary tool, you could probably churn them out in seconds.
Step 3: Safety
OK, I don't really have to warn you about safe use of blades, do I?
But, when you throw a poong stick, it can fly off in unpredictable directions, and it has a narrow, pointy end.
If there are several people using poong sticks at once, you should seriously consider issuing eye protection, especially if you are doing this as a group activity with children.
Step 4: Using the Poong Stick.
Hold the narrow section of the stick between whichever two digits you "click" with when you snap your fingers. That's probably your middle finger and your thumb.
Snap your fingers to make the stick spin as rapidly as possible, and make a gentle throwing action at the same time - after a little practice, the stick will shoot out of your fingers in an odd, spiralling trajectory, making an odd poong sound as it goes (why do you think I changed the name to "Poong Stick"?).
Step 5: The Science Bit
The Poong Stick generates sound as it spins - the air vibrates as it passes over the edges.
You can set your class the task of investigating how to vary the Poong Stick's sound - changing the length and width are obvious, but what about the thickness? Or how rounded the edges are?
Does a Poong Stick with a varying width give a mixture of notes? Does the material the stick is made of matter?
How would you measure the sound?
Could you make a set of Poong Sticks that will play a tune??
Step 6: A Year Later...
...and the school where I recorded that video doesn't exist any more, but the Poong sticks carry on.
I met Martin Raynsford at the Derby Mini Maker Faire 2012, and while I stood there, he drew up and cut a selection of Poong sticks (the middle one lives in my wallet now).