Sometimes seemingly random parts add up to a greater whole. For example: Grandpa Sam sired several agility champion Pulik; puppies need intellectual challenges; DezandNick received a delivery in a big cardboard box… hence,
Sassa considering the cardboard tunnel
the box-tunnel challenge! Uzi was willing to go in head first to get the easy to reach treats, then back out, but Sassa was first to go all the way thru the tunnel.
dezandpups 
We never thought of using boxes for agility! Otto just sees them as giant chew toys; we can’t put them on the ground before they’ve been emptied without risking bite marks on their contents.
Didn’t you used to store Otto’s chew toys in a wine box? (Clever; it’s amazing how doggie toys can take over a house.) Perhaps now he thinks all boxes contain a selection of toys for him 🙂