Styrofoam and Golf Tees

Tiffany--

I wish I had my camera with me so I could have taken a picture.
Here's what she did: ( a friend of Emily's) 

Save the solid rectangular pieces of styrofoam packing that come when
you buy stuff like computers, DVD players, etc.

Give your kid a bag of golf tees and a small toy hammer.

Let them spend an hour hammering all the golf tees into the styrofoam.

If they are a little older they can make pictures and designs with
them (kind of a la Light Bright)

I was a little surprised that it held their attention, but this kept
two three year-old girls busy for quite a while this afternoon.

Cost: $0, supposing you have this stuff around the house.