Just install angled “ball ramps” made out of scrap Wooden. The balls in shape neatly from the gap, and since the ball ramp is correct there at the edge in the garage, Young ones usually tend to use it. Can “itself” replace “by themselves” in the sentence "And getting autistic https://howtogeeks.co.uk/how-to-replace-your-garage-door-a-step-by-step-guide/