This printed great, and will be functional, but there is a "stop" at the bottom of the slots that the battery rails slide into that seems to be a little too tall. The arrow in the photo points to what I'm talking about. As I said, it's still usable, but the battery doesn't insert far enough to lock. I'd love to have a STEP file of this, so that I could correct it for my application, but I don't believe that's an option in TinkerCAD. NOTE: Disregard everything above about the fit. I just applied a little more force, and the battery popped in. If you print this and have the same problem, the tolerances are pretty tight. Just put a little more pressure on the battery. It fits as tight as some of my Dewalt tools. Note that it will also require a good bit of umph to remove the battery. Once it's locked, it's not going anywhere by accident. Great design!!

Here's a couple more photos of the battery supports in action, with two more types of batteries. Both work great, even better when securely mounted to the wall. This will be very handy. Thanks!