Is to keep the plastic cores on the inside and use just regular earplugs as new foam material. To do it properly, you do need to buy a proper hole punch, a pin to create a guide, a hammer and some goop as an adhesive, but once you do that, you basically have a set of 'comply' tips thats made with better foam, costs pennies per pair, and since they're so cheap, you can 'risk' washing these every day. I use p-series tips, and those require a 3mm punch, not sure about the larger tips. With this hack, I now have 2 pairs, that I rotate between and wash every day. The earplug is of a better, denser quality. Although I've washed them so many times, it's lost it's memory foam capacity. Probably lost a couple of db in isolation, but after washing every second day, the foam has held up pretty well and not degraded like comply foam would. Not that it really matters, if I wanted to, I would just get another 30c plug and make 2 pairs out of a set of plugs. For me the 3M Earfit seems to work with me the best.