I use a rod wrapper with the V style supports. I put a screw on each side of the V. Each screw is lower than the bottom of the V by just a tiny bit.
I hook an elastic hair tie over one screw, then over the blank that is resting in the V, and hook it over the other screw. This puts enough tension on the rod blank to keep it from rotating when I take my hands off of the blank.

It's simple and it works.