I always encourage my children to participate in doing thank you notes. Once I had my son paint with watercolors and then once dry, I cut the page into quarters and glued them onto notecards. On the back, I gave him credit with his age.
When my daughter turned two, she received so many lovely gifts and she was more than happy to play with each one for a quick photo. I printed out the pictures, glued them onto card stock and used a ducky rubber stamp on each card to go with our themed ducky party.
I hoped our guests enjoyed seeing their nice gifts again and being thoroughly enjoyed!