What does the inside of a guitar look like?

The inside of the cello is hollow. There is a sound posts (wooden dowel) that presses against the treble side of the front and back of the cello, to help with the sound. There is a bar that is glued to the top which strengthens the bass side. There are 2-6 blocks, one to support the neck, one for the endpin and 4 for the corners on most instruments.