Recycled Bottle Guitar (3 Parts, NO Tools)

This project is one of the simplest, fully functional guitar designs you will ever see. It requires only three parts: a 2 liter bottle, a 3 foot (90cm) length of PVC pipe or wooden dowel that fits inside the bottle (in the US this is a 1/2" pipe for the mouth of a standard soda bottle), and a string about 3x longer than the pipe.

To listen to how this guitar plays check out the full video here:

The trickiest part about assembling this guitar is learning the different knots used in stringing it up. Once the knots are learned the actual building process only takes 2-3 minutes. We'll start with the one and only bit of work that needs to be done to assemble the body of the guitar before focusing on the string.

Step 1: Filing a Notch

On the top of the neck, this guitar will need a notch for the string to rest in. To accomplish this you can use a file, but my goal was to design this guitar to be easily made without any tools at all. Filing the groove is easily done on the edge of a sharp stone or cement stairs. Once finished the pipe can be inserted into the bottle to act as the guitar's neck, and it's time to string it up!

Step 2: Learning to Tie a Bowline Knot

Stringing the guitar starts by looping the end of the string around the bottom of the bottle as shown in the first image above, then tying a knot that will rest half way up the side. It's important that this knot doesn't slip, which makes it a great place to use a bowline. The bowline knot is one of the most commonly used knots among sailors, tree workers, and most professions that involve rope. It forms a loop that will never slip, and even after being tightened with thousands of pounds it remains easy to untie.

In the above image series I demonstrate one of the most intuitive ways I've learned to tie a bowline, by holding the end of the rope between two fingers with your palm facing down. These two fingers are then looped over the other side of the rope in a twisting motion to result in your palm facing upward, and the line that was between your fingers now going through the center of the loop that was created. This end of the line then goes behind and around the "tree", and back through the hole. Tighten it up and you have a bowline.

This is the knot that should be tied in the guitar string, and positioned so it rests as shown in the final image in the series. Note: the string I am using for the guitar is a fairly strong synthetic gardening string. The thickness of the string will determine how high (or low) of a note the guitar can be tuned to. A string as thick as a clothesline can be used for a bass guitar.

Step 3: Tying a "guitar Tuner" Knot

Once the bowline has been tied on the front of the instrument, the string is looped over the end of the neck (so it rests in the notch filed earlier) and brought all the way down to the bottom of the bottle. The string then wraps back upward once again to form another loop, this time secured by a very useful sliding knot that will act as the guitar's tuner. This knot is called a taut line hitch. As it's name implies a taut line hitch is used for tightening a line.

Again the above image series shows the steps for tying this particular knot. The end of the string is looped around the trunk, twice. Then it passes over itself, back under the trunk, then up and through the opening above. This forms a knot that will slide easily if the knot itself is grabbed and moved along the rope, but when the end of the rope is pulled the knot self tightens to prevent sliding. By tying this knot on the back of the instrument, it can be slid to tighten or loosen the guitar string and in that way it serves the same purpose as a guitar tuner.

Step 4: Adding the Bridge

All guitars need a bridge to lift the string off the body, which in this case is a soda bottle. Once the string is tight thanks to the taut line hitch on the back, the cap of the bottle can be slid under the bowline knot in front. This lifts the string off the surface of the bottle which improves the guitar's resonance (volume), and reduces undesirable buzzing. Adjusting the bridge position can change the tone of the instrument dramatically so it's worth moving it around to find where it sounds the best.

Step 5: Playing the Guitar

A one string guitar is commonly known as a diddley bow, and many tutorials are available for playing instruments of a similar design. There is no need to tune the instrument precisely unless you plan on playing music with others, as with only one string there's no way for it to sound out of tune. A simplified version of just about every song is possible to play on a single string, and the best way to learn them is finding the notes by ear.

In the full video for this project I demonstrate several other modifications to these guitars, including using thinner strings (which requires learning a third knot), as well as adding frets and lowering the guitar's action. These things are not required for the simplest version of this bottle guitar, but you may like to watch the video to see/hear the differences between versions.

I hope to see a lot of guitars made in this style as I'm quite happy with the simplicity of the project, and with the educational value of learning the knots involved along the way. This would be a great intro to knots for something like a boyscout group.

I hope you build one and enjoy it!

Again here is the full project video with a demonstration of the guitar's sound: