Family Tree with Thumbprints by Elisabeth Ventling

We are planning a family reunion this summer and I think we should do a thumbprint tree like the one above available in the ElisabethVentlingArt shop on Etsy. While not a tradition family tree showing relationships of one member to another, this kind of tree captures those who are there at the family reunion. It seems like young and old alike would enjoy putting their mark on the tree. Have you ever done a thumbprint tree?