We had a little time to fill in W.'s class when we did our two hands art projects, so I gave the kids plain sheets of paper and told them to make another hand project, using crayons and watercolor paint if they wanted to. The top picture is what W. did. She copied around her hand multiple times, overlapping the fingers some. Then she colored them in, each with different colors, overlapping the colors where the fingers overlapped. Then she colored in the background. (Not shown.) I think it was very effective. You could also do the hands colored in and then do a watercolor wash over it all for another great variation.
The bottom picture was a cute idea a couple of other girls tried. This would be fun for a birthday party. Each girl traced around her hand with a crayon, then signed the inside of her outline. This would be a fun way to collect your friends's handprints and signatures. Or it would be fun to do with a whole family and frame it when finished. Again, a watercolor wash over it all at the end would make a cool finish.