In the past I've messed around with some "Pick 'N' Pluck" foam, but found it not to be very durable. You really have to be gentle with it. It seems to work best if you play Golden Melodys as they have rounded edges! The main problem I've had with "Pick 'N' Pluck" is the "out gases" it creates. It gets in your harps and then you end up breathing it in. I might have come up with a way to permanently connect the top and bottom of the foam after you pick 'n' pluck out the sections for your harps, making the foam more durable (it will take some time for me to perfect this, if I even get back around to it), but I can do nothing about the "out gases". I've had foam inserts sitting out in the open for months now, and they still smell just as they did when new! So I guess I wouldn't recomend "Pick 'N' Pluck" for harmonicas. I've only really tried two different brands of foam tho.... maybe someone has had better luck?