Things You Will Need:
Painters tape or masking tape
Ziploc freezer bags
Paint (or similar colored substances such as hair gel or shampoo)
Squirt the paint into plastic bags. You can use just one color or try squirting in two primary colors of something like tempera paint, and turn it into a great color-mixing experiment for your child as well. From here, there are two ways you can proceed -- one is slightly messy (for you) and the other is completely mess-free.
The second option is to place the paper on the table (outside of the bag) and then tape the closed bag over the top of the paper. If you choose to do it this way, the bags (and the paper) can be reused for as long as the bag will hold up.
And on days where you're in a particularly good mood, good old-fashioned regular finger-painting is always an entertaining and popular way to pass the afternoon.
Information taken from: