Here is a demonstration of how it sounds.
Step 1: Materials Needed
Shown in photo:
-2" ABS/PVC Piping
-2" ABS/PVC Elbows
-2" ABS/PVC Couplings
-Pipe cutter (a hacksaw will work too, but it makes the edges rough)
Not Shown in Photo:
-2x4 and 2x10's
-2 1/2" Bore
-Power tools and screws
-Castor Wheels (Optional)
Step 2: The "Keyboard"
I used 2 2x4's cut to about 6 feet to make my keyboard. One section was used for the sharps and flats while the other was used for the natural notes. Use the 2 1/2" bore to cut the holes for the pipes. On small gaps, the centers of the holes should be 3 1/2" apart. On the larger gaps, 6 1/2" apart. If starting on a C, space the holes correctly as shown in the picture.
Step 3: Building the Base
The size of your base will depend on how many notes you choose to use. Mine ended up being a little more than six feet wide. With the two keyboard sections, I created two tiers, placing the one with the sharps and flats on top. For comfortable playing, your bottom tier should be as high as your hand when you have your arm bent at a 90 degree angle. I installed castor wheels on mine to make it more portable, to do this, I had to put 2 2x4's side by side on each side of the base so that there was a wide enough space for the wheels. Where the wheels were placed, it is extended out so the instrument does not easily topple.
Step 4: Paddles
My paddles were purchased online but you can make your own. You need to get closed cell, dense foam similar to the foam used in flip flops, but flip flops are a little more dense than what I have. You can cut up and use the foam from flip flops. Whatever you decide to use, attach it to some sort of wooden dowel or anything you can find that would work. Experiment with the paddles until you find what you like.
Step 5: Assembling the Pipes
This is one of the trickiest parts of the whole process. The pipes will hang by the couplings, the pipe is small enough to pass through the hole, but the coupling is too large to pass through. As you add more notes, you will have to add turns to the pipes so you have enough room. Once a note is installed, use the tuner to fine tune it, making minor adjustments to do so. I recommend starting from the bottom because the notes get shorter as you move up. My lowest note was about 8 feet long, which required it to go down, travel across the instrument, then go forward. My highest note was around 1 foot long.
I got an equation from nate true that will give you the length of the pipe you need when you plug in the frequency: Tube Length (in) = (13300/(2*Frequency))+(Tube Diameter/2)
For the frequencies of the notes in the range of the piano go here: http://en.wikipedia.org/wiki/Piano_key_frequencies
My low note was number 16 (C2) in the list on the wikipedia page.
Remember, if a note is too sharp, it is too short. If it is too flat, it is too long.
Step 6: Finishing Touches
You do not need to glue every single joint. The best places to glue would be at the couplings or anywhere a joint is bearing weight. When not glued, notes can fall off while playing. This becomes very annoying! You might also want to consider installing something to hold your paddles when you are not playing.
Please let me know if you have any comments or questions.