I always love when I can combine an art activity and a play activity - or, in other words, make something to play with.
These Egg Carton Aliens are super easy and will allow your child to really use some creativity to make toys that they will, hopefully, play with for a while.
All you need is an egg carton (use some scissors to cut out the individual cups), tempera paint, and some alien creation goodies (googly eyes, fuzzy craft balls, etc.).
Start by letting your little one paint the egg carton cups.
Once dry, you are ready to decorate. For kids that have some difficulty with the creative process (i.e. get frustrated when they have to come up with idea on their own), you may want to make a model for them first and then ask them to make the same alien as you. Or, you could try taking turns, "I put on an eye. You put on an eye."