Using an DC Adapter for Battery Powered Device

This Instructable will show you how to use a DC adapter instead of batteries. By using a DC power supply, you won't need any more batteries which makes the device cheaper to run. The battery imitation here made of bamboo.

Based on the tables, electricity gives you more bang for your buck than alkaline batteries. AA batteries cost $330 per kWh and electricity costs $0.10 per kWh, which is more than 3000 times as much!
Source: http://www.buchmann.ca/Article1-Page1.asp

"Battery" Piece
Bamboo stake (available at garden centers)
DC adapter
Aluminum foil
Two pieces of bare copper wire
Markers to label the polarity

Conductor Piece
Bamboo stake (quantity depends on the number of batteries you are replacing)
Aluminum foil
One piece of bare copper wire per conductor piece

Tools:
Wire strippers
Pliers
Saw
Hot glue gun
Soldering iron
Drill
Sandpaper

The bamboo stakes in my garden perfectly fit AA battery holders. For the project, you will need to make one "battery" piece and at least one conductor piece. They'll be slightly shorter than the batteries, and the ends filed.

"Battery" Piece
To make the battery piece, cut a hole in the center length of the bamboo and arrange the wires, as shown in picture 2. Loop the ends of the wires. You can clip the connector and save it for other projects. Hot glue can be used to keep the wires from moving. Never let them touch!

Conducting Pieces
The conducting pieces may or may not be needed at all. They take the place of the other batteries. To make the conducting pieces, put the copper wires through the ends of each piece and loop the ends to keep them from falling out. Make sure their wires don't touch their neighbour's. If there is poor contact, you may fill the ends with aluminum foil

If you want, you can also make a USB Bamboo "Battery" by using a USB cable instead of an adapter.

Warning:
Always measure the voltage before using it, make sure the adapter doesn't overheat.