The other day I wanted to do a shape activity, but didn't want to take a lot of time to prep it. I came up with this. I simply took a piece of paper and drew several shapes on it. They aren't perfect (as you can see). Then I told my children to color the diamonds on the page. This picture is the one I did for my 6 year old. It was rather simple for him. I did fewer shapes on the page for my 4 year old, and even fewer for the 2 year old.
If you wanted the shapes to look nicer, you could definitely make this in Word with the shape tools and print it off.