I needed another battery car for the 2nd simple critter control I had. This time I used a HLW boxcar. It worked out nice because it has a removable roof so I can switch out batteries. I als needed something that would allow me to use different size batteries. I still have a little work to do but overall it worked out well. I put the Critter control on the side and used the brake wheel as my throttle. I also put in a reverse switch by the doors. The batteries I am using I got from a friend. He works for the plane industry and gets the batteries when the shelf life expires on the them but they are still perfectly good just not for use on planes. He made up a few packs for me. They work great and were free 
Just have to paint by the brake wheel and secure the battery pack to the base I made.
