Quick Question

Then that would work with something like Thomas and Friends right or was that what you were saying??

That's exactly what I was saying sort of , you could potentially build the drive/battery into the body of the larger engines, but for the smaller ones like Thomas you'd probably need to put it into a carriage or wagon. Thing is if they are small carriages like Thomas's ones the scale would be a bit odd as they wouldn't be long enough for the mechanism. Unless of course they decided to use those half length AAA's...