I have solved my problem thanks to you. I made DC coupler (battery shell) for Canon PowerShot SX150 and similar cameras that uses 2 AA battery. I made also 3.15V regulator for DC coupler, but I couldn't prepared how to video.
Ingenious! Every detail is plain. Good job! There have been times I wanted to make something the size and shape of a battery. Now I look around and I see I have plastic syringes from inkjet refill kits but it never occurred to me to turn them into battery shells.