CrownKing offers one, but it's already got a knot in it (2 separate knots actually, that unscrew and can be swapped at will) but they're 2 synthetics. I have 2 synths that I like (and a 3rd that's okay, it's my cheap travel brush) so I don't need 2 more. This intrigues me because I can put whatever knot I want into it! will it be a 2 piece handle that the neck screws off or a solid handle? Have you considered making a 2 piece and selling the "cap" that holds the knot separately to allow multiple knots to be used with the same handle?