What is a Mandala?

Mandala, (Sanskrit for circle) is a traditional form of Tibetan Buddhism. Mandalas are drawings in three-dimensional forms of sand. In Tibetan, this art is called "dul-tson-kyil-khor", "mandala of colored powder".
Millions of grains of sand are painstakingly laid into place on a flat platform over a period of several days.

After spending days placing each grain of sand into intricate patterns to form a beautifully detailed picture, the monks destroy their work by sweeping up the colored sands and dumping them into a nearby source of running water so that the healing energies can be spread throughout the world. This ritualistic destruction is supposed to symbolize the impermanence of all things.
Mostly made of colored sand, a mandala can also be created in powdered flowers, grains or herbs. In ancient days, precious and semi-precious gems were ground into a powder and used.

There is a ritual to creating a mandala that begins with an opening ceremony. The monks consecrate the site as they call forth the forces of goodness by chanting mantras while others play flutes, drums and cymbals.
After the ceremony, an outline of the mandala is drawn on a wooden platform, so that over the next few days, colored sand can be poured into the pattern using tiny metal funnels called "chakpur." To get the sand to flow through the chakpur, the funnel is scraped with a metal rod to cause enough vibration for individual grains of sand to trickle out of it. The two chakpurs symbolize the union of wisdom and compassion.
All mandalas have three meanings an outer, an inner, and a secret level of meaning. The outer level represents the world in its divine form. On the inner level, the monks create a map by which the ordinary mind is transformed into the enlightened mind. On the secret level, the monks predict the primordially perfect balance of the subtle energies of the body and the clear light dimension of the mind. Making a mandala is supposed to cause purification and healing on all three levels. http://www.gomangtour.org/goal.html