What’s the best way to “weaken” a cardboard box to make it easier to break?

Answer from Piñata Boy

If you’re decorating with something like crepe paper, you can just stab holes in the box a kitchen knife or pair of scissors before decorating.  You can stab holes all over the place, or just where you want to create a weakness.  But if you’re using cardboard you’ll want to stab a LOT of holes — depending on the age of the kids you might need one stab per square inch or even more than that.  Don’t count them, just stab away for a while and then feel how resistant the box is.  If you think it needs more, add more.  What often happens when I do this is that I’ll accidentally make a spot too weak, and if that spot gets hit, it’ll leave a visible tear — once the kids see that they zero in on it and the pace accelerates.

If you’re decorating the piñata using paint, then creating weakness becomes more difficult because the stab holes are visible in the piñata, even if it’s painted black.  In that came it might be better to use a razor blade to score the inside of the box to weaken it from the inside.  But be careful not to press too hard and leave score lines on the outside of the piñata that might be visible after painting.  You can even score out little triangles from the inside to make “tearaway” spots that leave bigger gashes when they’re hit.

Good luck!