It is an experience rather than just a product. The person completing the picture uses their imagination to create the picture in the colours they wish.
For children it helps to build their skills and it is a lovely activity to keep the children busy for 30 minutes or for you to spend the time together while they enjoy creating their masterpiece.
Most of all it is great fun!!
If you are new to sand art why not take a look at this video and see what it is all about