How do I get rid of the smell of tennis balls?

: How do I get rid of the smell of tennis balls to dry a down duvet ?
It’s been recommended to use tennis balls to dry a down duvet; however the odour of the tennis balls is so strong, even after washing the tennis balls several times and drying them in the sun. I have used tea towels tied up in knots as an alternative, but I wonder if someone has an answer for the tennis balls.

Answers and Views:

Answer by saaanen
I have never smelled a smelly tennis ball. Use clean sneakers instead

Answer by Boggy
It is the down that smells. If it takes a while to dry it gets a horrid smell. Best to get down professionally cleaned.