I have posted this before. I got a new can of Plasti-Dip and was going through the process to dip some clamp handles and thought I would share how I do it. I put a 45* V bit in the table, set the fence for half the diameter of the handle to be grooved, add a stop so things stay neat and slid the handle through at 3, 6, 9, and 12 o'clock.
I lightly wipe the handles with Naphtha or alcohol just before I dip them to remove any oils that might be on them. I have tried other variations including no-grooves. The grooves really help with control on the smaller clamps (I notice this most when I have a non-grooved clamp in the batch I am currently twisting on) which are usually doing more delicate things. I plan to do the larger clamps I have that do not lend themselves to other methods I have used. Here's an old one:
The following pics are of clamps that were done 1 and 2 years ago. None have failed (even a little) including some of the ones where you can see I did not get it on very thick. Surprisingly resilient.