Polymer clay is just like Playdoh you can harden by baking. My kids had a blast making their own ornaments this year....and so did I. It was fun seeing their personalities come out in the ornaments created. Just play and form the same way you would do Playdoh or salt dough.
Also, polymer ornaments make good memory ornaments. I have several bitter sweet ornaments from before my strokes that bring on serious emotions. I'm sure that creating one for a lost baby would be very therapeutic, even if it was emotional.
FYI...cookie cutters make for easy ornaments. I found teensy ones, hence the little gingerbread men. I used a cookie cutter. It took about 1/4 block of Sculpey for each gingerbread man.