Hi,
I know they are available at B'lore. In Chennai, I think you can try asking in Triplicane, as Varloo suggests. I have asked my Athai to get me one mould from B'lore when she comes over next

. Actually, it is more famous in places like Dhavangre, Banashankari than Banglore! Do let me know when you find one in Chennai.
Cheers
Arch