I can play better on my guitar xD Just a little preview.

Plays awesomely! Sounds somewhat like an acoustic guitar. And for very cheap!

Step 1: Find Your Stuff

You will need:

Tape
A gogurt box
Rubber bands
Scissors
Ruler
Tape

Step 2: Patch Up the Box's Edges.

With Tape :D

Step 3: Cut a Hole

Cut the hole about 1 in starting from the bottom and make it these dimensions:

1.5 in x 2.2 in

Left side x top side

Step 4: Using the Scrap Cardboard,

Cut it in half either way.

With one half, fold it as much as you can to create a thick bump.
Tape it below your hold.

With the other half, tape it ontop of the bump. This is how we will elevate the strings.

Step 5: Put the Rubber Bands On

Put them diagonal and ontop of the cardboard which is placed on the bump. This will make sure to strings don't over-vibrate.

Step 6: Your Done!

Be creative! Everyone has different rubber bands, so it may sound differently each time. Enjoy your gogurt guitar!

Make sure if you post it somewhere give I, Emerald 28 credit.

Thanks :D