Two of my grandsons, who are brothers, celebrate their birthdays on the same day.
For my grandson who is turning four, I made a card using InkyAntics Birthday Elephant HoneyPOP stamp set. The stamp set has a template for a balloon using InkyAntics Honeycomb paper. When the card is opened, the balloon opens up.
For my grandson who is turning six, I made a pinwheel using SU's Celebrations DSP (retired).
I found that a six inch lollipop stick from AC Moore made a great handle for the pinwheel.