If you're tying leader and splicing lines sometimes it's handy to hold the line on one end and make it easier........
Here's a simple and inexpensive way to help your self. Just wrap a line around a couple wraps on the o rings, they'll pinch some and the line is protected and easily unwound.
A washer and a pair of rubber o rings and a screw should get it done ✅. The inside of the o ring should be about the screw, and the inside of the washer diameter slightly smaller than the o ring.
These parts are easily found at a hardware store Orin many dusty bins, drawers, from a friends garage.
This can be helpful when a pair of these o ring things separated on simple posts if doing boring half hitches, or long winding knots. Just saying.
Lastly I wanna apologize for masking the clutter on my fly tying vice.....😾
Fantastic third hand Gary, thanks for sharing.