What is "chak-pur"

Chak-pur are the tradition tools used in Tibetan sandpainting to produce mandalas. They are conically shaped metal funnels and often have ridges down the sides. Normally about in length, they taper to a fine point and are made with varying diameter holes at the end in order to disperse the sand in a controlled way. A Tibetan monk will usually tap glide a piece of wood over the ridges in order to slowly allow the sand to emerge through the hole through the vibrations created.