Full time power for Hess Truck display case.

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Hello I am looking for advice on how to have constant power to a battery powered Hess Truck. I was asked to make a display case for a collection of Hess Trucks and to provide power on a switch to turn the trucks on when desired in their display case. I have little to no experience with this type of electrical work and wonder if it is even possible. Thanks ahead of time for any advice you can give.