The first way I used this box was with one size of caps. I cut an opening in the box that was the same size of the caps and he simply pushed the caps into the slot. He loved watching and listening to the caps drop into the box. When this seemed to get too easy for my son, I created a second way to play with the box. I used bottle and container caps of different sizes and added more openings to the box. My son had a great time figuring out which caps fit correctly into each slot. This was an easy activity that cost no extra money to create. It is amazing how often I find that trash can easily be turned into treasured play experiences as shown in the two pictures above.