A Homemade Whistle in Less Than a Minute

In this Instructable I will show you how to make a quick whistle from a tin can.

When I was a kid we used to make these whistles out of jam tin lids. 

Apart from being a fun toy for kids, I think these whistles would be great working with dogs, directing cranes, or even to attract attention in an emergency. They are pretty loud and you don't have stick your fingers in your mouth - this can be a pain if you happen to be wearing gloves or your hands are dirty.
I have heard that similar whistles are popular with shepherds in New Zealand who use them for directing their dogs.

Materials
1 lid from a tin can
duct tape

Tools
A drill with a bit about 3mm
hammer and centre punch
A small piece of ply or something to bend the tin around. About 4mm thick.
A knife for cutting the duct tape.

Cut some duct tape into a strip about 10mm wide. Use this strip to cover the sharp edge of you tin lid.

Simply bend the tin lid in half around something (a piece plywood is perfect) that will maintain a gap of about 4mm between the two halves. Keep the ply in place and drill a 3-4mm hole right through the whistle. The hole should be about 5mm from the folded edge, about half way along.

Clean up any sharp bits from around the hole, and that's it.

Just look at the video to see how easy it is.

This part is harder to explain than making the whistle...

Place the folded part of the whistler against the bottom of your tongue.
Push your tongue back with the whistle so the tip of your tongue points at the roof of your mouth.
Let you lips gently seal against the top and bottom part of the whistle.
Blow.
Blow soft and hard and experiment with different mouth shapes until your make it whistle.
It might take a bit of practice to get started, but before long you will notice dogs and cranes desperately trying to follow your instructions.