I had the empty oatmeal container sitting on my counter for about 2 weeks before I finally figured out what to do with it (couldn't bear to throw it away!).
Using a knife, I slit about 8 holes into the top of the lid and gave G a handful of popsicle sticks to push through the holes. It was definitely a hit! They make a satisfying little "pop" when they slide in; plus- it's so fun to shake them around once they're inside.
I didn't anticipate it being a fun toy for M, but she wanted to play with it too. The nice thing about multiple holes is they can both do it at the same time if no one gets greedy and decides to pick up the container.