You're probably going to buy one, not make one... You do need a power supply with sufficient current if you are using any number of servos. I would say a 10amp power supply is a good start..

To elaborate on what Richard said; Wall voltage is AC Voltage. you cant run AC voltage through the EZB. You need to get a converter to change the voltage from AC to DC voltage. They are very common and inexpensive. Like Richard mentioned you need to know how much current (amperage) all your devices will be pulling. To do this you need to check each unit and add up the peek amps each will draw. This will tell you how big of a converter you'll need. Make sure you give yourself a little overhead. Also you'll need to decide how much DC voltage you'll need to deliver the amps to your equipment. For example if your math adds up to 10 amps at 12 vdc get the next larger converter. Here's a good one for this example:

12vdc, 12.5 amp AC-DC converter