All you need are tiny dinosaurs (I found mine for $2 a package at the grocery store) and Baking Soda (lots of it), and food coloring if desired. Plus vinegar to help the eggs "hatch."
Mix a large amount of baking soda with just a bit of water at a time. Add food coloring at this time if you like. The mixture should clump together but not be too wet. Next wrap the mixture around a baby dinosaur and set aside to air dry overnight. I had to hide our eggs in the oven so nosy eyes didn't happen upon them.
This afternoon the boys found this scene in the backyard and were thrilled to be tasked with the job of helping baby dinos hatch! Off they went with a spray bottle I filled with vinegar.
It's quite fun to watch the egg fizz away once the vinegar hits it. I decided to carefully move the eggs into a plastic tub as I was worried the vinegar may somehow ruin the grass. After Ryan had a go he asked Jackson to help, and he was happy to oblige.
This took up about 1.5 hours today. That's a win in my book!