Did I say easy? I meant ridiculously easy!
I got the containers at the dollar store (they are the perfect size for little hands!). Kay (who gets a little jealous that I'm baby-sitting her cousin during the day, so I wanted to get her involved in making these) helped me come up with things to put in them. We chose sand, beads, buttons, colored rice, jingle bells...things that would make different sounds when they were shaken.
I used clear packing tape to seal the covers on and presented them to my 7-month-old niece. No surprise - her favorites were the ones with the best noises! (The sand and the soft cubes are nearly always tossed aside!)
Like these? You might also like And Next Comes L's color blocks - they're lovely and made with dollar store materials, too!