R.D.
I cherish the first handprints I got from my son's daycare!! It was simple - the teacher painted his hands then pressed them on the paper then washed them off - but it was the greatest thing I had ever seen! He was only about three months old at the time.
Another favorite project is at Halloween. They took off a sock and painted his foot white, then pressed it on a black piece of construction paper. Once it dries, turn the footprint upside down (heel at the top) and draw two eyes on it with a black Sharpie for a super-cute ghost! Use a silver Sharpie to put their name on the bottom.
You can make fingerprint 'bugs' by drawing little antennas and eyes on them. Put them on a flower cutout or something similar.
You can cut out shapes and tell them what color and what shapes they are, then put glue on the back and let them place it on paper.
You can let them have a marker and let them draw (scribble or whatever) on a coffee filter, then spray it with water for "water color art." (That looks cool!)
Just the squishing of the paint in their fingers and talking about it (is it sticky? cool? squishy? gritty? watery?) is a good way to make brain connections.
I know there are books out there on the subject. Try searching home school books, the library, the preschool's resources, the Internet and mom groups for more ideas. HTH - GL!