how sri sathya sai baba creates sivling and other articles?

Answer 1

Just because he is a trained magician with an alternate profession which is more fruitful financially .

Answer 2

Baba begun to give signs of divine power from childhood." "At school, he used to create chocolates, marbles, and other articles for the children around him." From his very Birth,he acquire this divine Power.
Baba says:

"That is to say, I resolved upon My Birth. I decided who should be My Mother. Mere humans can choose only who is to be wife or husband: the Mother was chosen by the Son in the Rama incarnation and in the Krishna incarnation. Then too, the task for which the birth was decided upon was, conferring Prema (Love) on all, and through that Prema, foster righteous living."

"My acts are evidences of Divine Sakthi, signs and signals of Divinity. I am granting things out of Prema. My Prema will never diminish. I have no desire of any kind. I talk of Love, I guide you along the Path of Love, I am Love."

Lucky are the seekers of love and light, who get the privilege of seeing Baba, the perfect embodiment of being, awareness, bliss, Atma; witnessing His divinity, hearing His teachings of universal love and on pursuit of absolute truth