I have finished the fire truck busy board. (Well except for a few idealistic finishing touches). The best part is, both A & S LOVE it!!
The gear wheels work great, especially after I screwed them on (vs just glue). The key door latch is A’s favorite part. Right now the door bell just clicks, but it is wireless so I could make it work.
The board is made mostly of 1/2″ plywood (because that is what I had) and then on the back I attached four 2″x2″ boards to create a frame so the truck sits away from the wall.