You might try one of the flexible filaments and make a pad that would get attached via adhesive. I think the vantage of the Lee products is they work well and can be user replaced.

You could try dipping a finger in liquid latex multiple time which would work well until it came off or got really dirty. I was actually thinking of trying this myself. They also sell liquid silicone for mold making where you mix to parts together and it cures but not sure how well it would adhere to the plastic finger.