I love making hand print crafts with my kids since they are such cute keepsakes. Last year we made hand print Santa ornaments!
For your basic salt dough ornaments you'll need to combine the following:
1 cup flour
1/2 cup salt
1/2 cup water
Knead until smooth and then roll out to 1/2" thick. You can roll out to 1/4" for standard ornaments but for the handprints I like to keep it a bit thicker. Have your child press his or her hand into the dough and then cut a circle around it. Poke a hole in the palm of the hand (Santa's hat) using a straw and bake at 250 until dry (about 2 hours).
Once they come out of the oven and cool you can paint! The thumb becomes the pom pom on Santa's hat and his beard is the fingers.
One thing I learned is that salt dough becomes smoother the longer you knead it. We made Will's ornament first and the dough wasn't quite as smooth and it ended up with a little crack across it. So make sure you knead the dough well. For all of Santa's features I just used a black sharpie.
With our leftover dough we cut out shapes with cookie cutters and then I let Anne paint them however she wanted :)