I have found some stuff that seems to grab really well on just about anything. That's the black polyester drawcord that DIYGearsupply sells. It is dirt cheap at .21 per yard, small, light & strong, and it has a rough surface that seems to grab well. It has a small diameter that makes it ideal for using on tech line and zing-it too. I like it. That's my story & I'm sticking to it.