Boomwhackers are tuned plastic tubes that make a sound when you hit them on anything. Boomwhackers are everywhere from kindergarten classrooms all the way up to a musical group at Harvard called Thud.

Name brand boomwhackers can be purchased from boomwhackers.com. However, they are very expensive for some colored plastic tubes($25). This can be very hard for teachers to buy as the standard set only comes with 8 boowhackers tuned to a diatonic C major scale. For the full range of boomwhackers, it would cost you $128.

This instructable will show you multiple different ways to make your own boomwhackers(each varying in price) and will even show you the science of how the boomwhackers work. Each of these different ways will give your boomwhackers a different timbre, or sound. I will include a video of two of the options being played with name brand boomwhackers. One of these methods will also include an easy way to make octavator caps(more on this later).

This instructable is also entered in the Instruments contest so if you like it please vote for it here. It would be greatly appreciated.

Supplies

I will show you multiple methods. For all of them you will need:

A tape measure
Something to mark the tubes with
Scissors, an X-acto knife or maybe eve
Someway to color or mark the boomwhackers to distinguish the notes from each other

For the optional octivator caps you will need:

Hot glue gun
Some sort of small saw(I used a coping saw)
a thin sheet of plastic at least the diameter of your boomwhackers

Each method is made from a different material, but you can make them out of any tube really. I will show using two good options and explain how to use other tubes. You will need one of these three things:

Fluorescent Bulb Tube Guard(and electrical tape)
Golf club tubing
Various pipe-shaped objects you have laying around your house

Step 1: How a Boomwhacker Works

A boomwhacker makes a sound when you hit it on something. The shape of the wave that this sound makes is called a sinusoidal wave. with the open ends being what is called the antinodes. A node is a spot on the wave that will not move, or where the waves cross the middle. An antinode is where it moves the most, or where the waves hit the top and bottom. Because both ends are open, only half of the full sound wave fits inside the tube. This causes the wavelength to be twice the length of the boomwhacker. if you know the length of your tube then you can easily find the frequency and vise versa. To find the frequency you can divide 340(the speed of sound) by twice the length of your tube(the wavelength). To find the length of your tube, you can divide 340 by the frequency of the tube. The number you get from this will be the wavelength, so you will need to divide this by 2 to get the actual length of the tube. If you know the length of one tube for a certain note, then there is an easy way to find the length od the other notes. The ratio of a note to the note a half step above that is the 12th root of 2 to 1, the ratio for a whole step(3 half steps) is the 12th root of 2 squared to 1, the ratio for 3 half steps is the 12th root of 2 cubed to 1, and so on. This is because of the ratio between a note and the same note an octave higher is 2:1. So, to make each half step an equal ratio, we use a 12th root of 2, because if you take the 12th root of 2 to the 12th power(the number of half steps in an octave) then you get 2. the radius of the tube plays no role in this equation, so no matter what radius tube you use, it will be the same pitch. For further reading on this, you can visit this site.

Step 2: How an Octavator Cap Works.

An octavator cap is a cap that is added to one end of the boomwhacker to seal it off. When the cap is added that end of the boomwhacker will, instead of being an antinode, be a node in the sound wave. The open end is still an antinode. This makes the length of the tube 1/4 the wavelength. Because this is twice the wavelength of the normal version of the same length tube, it makes it an octave lower. Because the ratio for an octave is 2:1. The second picture is my homemade version of an octavator cap and the third is the name brand kind. For further reading on this, you can visit this site.

Step 3: Where to Cut Your Tubes

I am only making the first five notes of a C major scale but will tell you how to make a whole octave(starting at middle C, of C4). To do this I would suggest using an X-acto knife, scissor or maybe even a small saw depending on your material of choice. The reason I suggest Golf club tubing and fluorescent light guards is because they are cheap, readily available, easy to cut and make a good sound. The golf club tubing is a good option if you already have name brand boomwhackers because they have similar timbres. You can cut the tubes to these lengths:

C4: 25.125 in
C#: 24.125 in
D: 22.75 in
D#: 21.5 in
E: 20.25 in
F: 19.125 in
F#: 18.125 in
G: 17.125 in
G#: 16.125 in
A: 15.25 in
A#: 14.375 in
B: 13.5 in
C5: 12.75 in

(C5 is not exactly half the length of C4 because of rounding). You might want to cut each note a little longer so that you can tone each note with a tuner or an online tuner such as this one. To increase the pitch you can cut a little off, but you can't decrease the pitch, so be careful.

Step 4: How to Make an Octavator Cap

If you chose to use the fluorescent light shield then you will have the option to make octavator caps with the ends. All you need to do is cut off the right before after the lip that goes around the end of the tube and then hot glue a thin sheet of plastic on. This will cause the boomwhacker to be a little out of tune, but it doesn't make that much of a difference.

Step 5: Adding the Color

In boomwhacker music, there are universal colors that show different notes. You can use paint or colored tape to show the different notes. However, if you use the fluorescent light shields or tubes like that you will have to add a strip of tape to the end. This is because they are kind of flimsy and when you hit them they will make weird pitches other than what they should. This can be fixed with a strip of tape(I used electrical tape). You can use these colors for your boomwhackers:

C: Red
C#: Red-orange
D: Orange
D#: Yellow-orange
E: Yellow
F: Light green
F#: Green
G: Dark green
G#: Blue
A: Indigo
A#: Purple
B: Light purple-pink

Step 6: Play With Your Boomwhackers

Now that you finished your set you can play different songs with them. One easy way to find music is to just look up "boomwhacker music" and you can find lots of different easy music to play. To play them all you have to do it hit them against another surface, your body, or another boomwhacker. If you hit 2 together they both make their respective note, so then you can play chords. Try not to hit them on sharp edges so that they don't dent. Happy whacking. I have added a video of me playing with the name brand version and two homemade versions. The audio quality is low but you can start to hear the difference in the timbres at the end.