I am purchasing a first edition hard backed copy of a book that is my husband's favorite book to give him from our kids. Our youngest is 4 months old and I was going to just put her handprint on the inside cover for him along with a note. I am not sure what to use to do the handprint. I don't want to use an inkpad because of it staining her hand (and let's face it, we all know kids that age constantly have their hands in their mouths). Any suggestion on something kid friendly to use???