Stuck on level 3

[Zeewolf]

You destroy the box using an explosive ketchup bottle.

Spoiler below!

Put the box under the big pipe on the first floor, then push the buttons on the "second" floor so that when you drop stuff onto the forcefield, it will exit through the first floor pipe. Then drop some explosive ketchup down there. You can get more ketchup from the small pipe near the big fan on the "second" floor.