Christmas micro lights for passenger cars?

Here's an idea I did on some HO cars with plastic wheels. Get some micro slide switches,coin battery holders and coin batteries. Hot glue your favorite led lights to the roof, drill a small hole in end of each car's doorway and hot glue a microswitch,glue the battery holder on the car's floor and solder wires from battery holder to switch and led lights.  Works well and is cheap when you buy the switches, batteries and holders in bulk.  I think it cost maybe 1.50 each car to do... Did this for old gondolas, that I repainted xmas colors that had no center pickup roller and knew the kids were goingto play with them. Would also work for outdoor G cars with plastic wheels.

Doing the ac/dc converter can be done and small ones can be found. Lots of topics here on doing that. All depends on how much you want to spend. Just like cars, how fast do you wannna go ?

Gunrunnerjohn's module is about as big as the end of your thumb, and led light strips are very inexpensive. That would be my choice.