Every year when Durga Puja approaches, a certain Kumortuli in Kolkata is thrown into frenzy. Kumortuli is the land of artisans in North Kolkata. They supply the idols to most of the pujas. Making the idols of Goddess Durga, along with Goddesses Lakshmi and Saraswati and Lords Ganesha and Kartikeya is a daunting task in itself. For the entire puja to be auspicious, the idols need to be created with the right mixture of punya mati or blessed soil. Source: The Hindu
Some believe that this custom is an attempt to include the section that is considered fallen and sinful. Most of these women are considered beneath any social standard. So, why do this once a year and shun them again after the puja is over? Why do this at all?
Source: PANOS
Then there are others who believe that this custom originated as a tribute to the courtesans, who were known for their proficiency in the arts. But of course, the definition of courtesans has been vastly altered in the course of time.
Source: Tumblr
No one has answered these questions. And the residents of Sonagachi still remain perturbed by them.
Whichever way, the custom still holds. By the time you read this, punya mati from the nishiddho pallis would long be gathered and the idols about half-made for this year's Durga Puja.