This is a really easy (and cheap) craft to do with kids. All you need is cardboard cut into egg shapes (cereal boxes are too thin), aluminum foil, paint (we used the big bottles of non-toxic, washable paint), paint brushes, and cotton swabs.
Start by covering your cardboard eggs with aluminum foil. After eggs are covered, start painting! You can use as many colors as you want, I just let my 3 year old choose two because it made it a little easier for him. After you paint, while the paint is still wet take your cotton swab and draw designs in the wet paint. Then let dry!
Here is the finished product!