Singer in Northwest
As a professional singer I know how important it is to keep my voice in shape. I have recently come across a Lax Vox tube created by doctorvox (you can find this on YouTube). This is a fantastic device that can be used as a regular warm up for the voice, or as an aid to help the voice to return to its healthy state due to overuse or when a singer is having vocal problems.
You need to watch the demo as this shows how much water needs to be in the bottle and how to do the exercises.