Have you seen these toys that come inside an egg and hatch? They're so popular, last Christmas they sold out. Well, as most of the kids my daughter wanted one. She loved it, but it only hatches once. Now that I found out how to make one with only 3 ingredients, we've been making them at least twice a week! She loves them.

With only three ingredients, plus a toy that could be bought in a second hand shop, this could be the perfect stocking stuffer for this Christmas.

What makes it extra special is that kids don't just open the toy. They'll be delighted with the experience of making it hatch. I'm sure they'll never forget this cool present.

Step 1: Gather Your Ingredients

You need of course a toy to hide inside plus these three ingredients:

1/4 cup baking soda
2 teaspoon water
1/4 cup vinegar

This amount covers perfectly our littlest pet shop toys that are about 1 3/4 inch. If your toy is bigger or you want to make several eggs, just double or triple the amounts.

Step 2: Mix.

Start by mixing the baking soda with the water.

You'll have a crumbly dough. It needs to be a little bit dry, but if you press it between your hands it should stick together. If it doesn't stick add a couple of drops of water until you get the desired texture.

I guess the best way to describe it is like moist sand for a sand castle, if you put too much water it won't work, too little and it won't stick.

Step 3: Hide the Toy

Now you can hide the toy. If you are afraid it'll get damaged with the baking soda and vinegar, you can put it in a small bag. Our toys haven't got damaged even after hatching multiple times. (And yes, my daughters get excited to make it hatch even if we are recycling the same toy, oh kids)

Grab a small amount of the dough and press it between your hands, then put the toy and add more dough to cover it.

Press and add more dough if needed.

Check all around the egg to see if the toy is well hidden.

At this point the egg should be formed but is very brittle. And just like a sand castle it could break just by holding it, so carefully put it in a surface where it can stay undisturbed. Let it dry for 24 hours.

Step 4: Optional: Use a Mold

You can use a mold to make it even prettier. I had this spherical one, but I wish I've keeped those plastic eggs from Easter, those are the perfect molds.

To use the two piece mold, put a layer of dough and press. Then put the toy and add more dough.

Cover the other side of the mold with firmly packed dough and join the two pieces. There should be dough leaking from the seam, that's how you know it has enough mixture.

Leave the mixture in the mold for at least 6 hours, then carefully take it out and let it air dry for 24 hours.

Step 5: Decorate the Eggs

Now after 24 hours they should feel like rocks. But handle them carefully because they could still be fragile.

Decorating the eggs is optional but fun. I've been testing different techniques for decorating them. These are my favourite:

To let the kids decorate their own eggs: with an old tooth brush and acrylic paint you can make nice speckles.
If an adult is decorating: With markers you can draw dots or other designs. Just be careful not to poke the egg with the markers.

Step 6: Let the Fun Begin

To make it hatch, kids will need to pour the vinegar in the egg. With adult supervision of course. The egg will start fizzing and revealing the surprise.

For an easier clean up first put the egg in a container.

My daughter's favourite way to make it hatch is by spraying the vinegar. Just find a small spray bottle that's easy to handle for the kids. Some sprayers are easier to handle for younger kids (like the ones with trigger, that one is perfect for my 2 year old daughter) The ones that requiere the index finger to press are suitable for older kids.

Finally remember to rinse throughly the toy.