I've recently picked up knife making for a hobby, and as a result ended up making kydex sheaths for them. I also have gone back and replaced the sheath on several other knives I owned (yes Doug, I replaced my Mk3 sheath; love the knife, hated the factory sheath).

For those of you wanting replacement/custom sheaths for some of your own knives, look into making your own out of kydex. There's more than enough resources online to easily learn how to make your own, and the materials themselves are cheap. I'd be happy to answer any questions if you have them.