1) Ask a adult to heat 1/2 cup of water to it boils.
2) Then take the pot off the heat. Then add 2 drops of food coloring. I use Gross Green
3) Add 3 packages of unflavored gelatin and stir for a couple minutes.
4) Then add about 1/2 cup of corn syrup so you have about 1 cup of thick mixture.
5) Stir with a fork and lift out some long strands of gunk.
6) As it cools, you might need to add water, spoonful by spoonful.
You have just made fake or artificial mucus.
Mucus is mainly made out of sugars and protein. That is what you used to make your fake mucus, only you use different proteins and different sugars.
Those long, fine strings inside your fake mucus are proteins. They are why real mucus can stretch out quite long. Come on we all know some one that has strength their mucus.
The protein helps make it sticky, too. The protein in your fake mucus is gelatin.
Here is some gross science. Put a pinch of fine dust or flour onto your fake mucus. Now stir it up. Look closely into the goo from the side. The fine dust/flour is trapped. That is why you have mucus in your nose. You use it to trap all the dust, pollen and junk that is floating in the air. With mucus, most of the dirt is trapped and then blown out.