Sound proofing materials/ motorcycle helmets (Briston NR24)

Hi. Does anyone have a small quantity of Sound-Absorbing Material? A few square feet should be enough. The egg carton style foam would be ideal.

                    Or would aldo consider


old or broken or compromised motorcycle helmets. Would prefer open face but full face will do. Going to be modified alternate use so don't want to take a good one out of circulation. Thanks for reading