Multiple Circuits to one power source
I am working on finalizing a circuit bent sculpture I've done for my undergrad thesis. I have three circuit bent items, each with it's own battery source within the sculpture. Here is my dilemma: normally I plug in the batteries when I show it to someone, then promptly take them out, but for my gallery show, the sculpture will be turned on for an extended period of time each day, in my absence. What I would like to do is connect all circuits to one battery source or AC power. After that I can add a switch so that the gallery attendant can turn in on/off as needed. I am looking for any tips on how to do this. As of now, one runs on a 4-AA pack, one on a 2-AA pack, and the last on a 9-volt. Adding these together I am getting 18V(?) and I have an old laptop adaptor that has an output of 18.5 volts. I have a video of the piece functioning if anyone is interested.
Thanks for your help (in advance).