Rampal, who will be taking on the part of a Bollywood actor in Madhur Bhandarkar's Heroine, revealed that it was important that he did not simply play himself.
The Housefull star told Mid Day: "I am not telling you whom I'm going to model my character on. But I won't deny that I'm borrowing traits from people I've observed from close quarters.
"In theory it sounds easy for me to play an actor, because I am one myself. But Madhur Bhandarkar doesn't want me to play me. We are working on creating an entirely new character. I want to show the dark and vulnerable side of the man."
The star will be seen performing opposite Aishwarya Rai Bachchan in the project, which is said to explore the underbelly of the Hindi film industry.
Rampal and Khan have collaborated together on a number of earlier films, including Don and Om Shanti Om.
The filmmaker announced his latest production at the Cannes Film Festival last month.