I've been recording a song entitled My Glass Head. I wanted to create a different vocal sound in the beginning and end of the song. I wanted some kind of closed-in, claustrophobic type of sound. I searched around for a barrel and trash can but couldn't find anything. Then it dawned on me that there can only be one item for this.
The picture shows how I set up the mic. Basically I had to lean over and sing into the opening. I positioned the mic and changed polar patterns until I got a sound that works.
So my glass head actually is a part of the song entitled My Glass Head.