My son is a paleontologist in training. Anything with fossils, bones, or dinosaurs just makes his day. He absolutely loved the idea of burying a dinosaur in soap--plus, I didn't have to convince him to take a bath for weeks!
First, empty the packet of gelatin into the bowl. Then, (this is an adult step) pour in the hot water and stir until the gelatin has dissolved.
Next stir in about 20-30 drops of food coloring. My son loved squirting lots and lots of drops, so I let him do it in a separate container.
Pour the mixture into the mold. We used an aluminum bread pan, but I wish that we had a glass dish--it would have been cooler to see the dinosaurs through the sides.
Then send your dinosaurs in for a swim! In order to cut the soap bars out later, you'll want to try to arrange the dinosaurs so they aren't too close.
Place your dinosaur-gelatin-soap in the fridge for about an hour (it will harden just like real Jell-O!). You can cut out your soap with a butter knife (or a cookie cutter if you want to get fancy.)