You may think that this isn't cardboard, but think again. This is a working cardboard guitar. I have 4 normal guitars, and this cardboard one. This is a moderately difficult build, but nevertheless amazing. This works just as well as my wood ones.

Supplies

Cardboard

Tuning Pegs

Guitar Strings

Eye Hooks

Metal Coat Hanger

Piece of Metal

Step 1: Making the Body

To make the body I Traced a wood guitar onto cardboard and cut two of those. Then, I got more cardboard for the perimeter and attached the two.

Step 2: Making the Bridge

To make the neck, I cut 5 layers of cardboard and glued them together. Then, I added a piece of metal on the back to stabilize it. I covered this piece of metal with cardboard. For the neck, the less flexible, the better.

Step 3: Adding the Frets

To make the frets, I cut a metal coat hanger into multiple pieces. I glued these on the neck as frets. To find the positioning of the frets here is a resource I found helpful. https://www.stewmac.com/FretCalculator.html

Step 4: Stringing the Guitar

To string the guitar, add the tuning pegs to the end of the neck. Then put the eye hooks at the end of the bridge. After this add the bridge and the pick guard and you are done. Now, you have a working cardboard guitar.