I have treated lots of scopes with Cerakote and they turn out nicely, including several I have done in a camo. Much better for hunting than the shiny or stainless finish.
Use a green scotch bright to rough up the surface so that the paint/duracoat or what ever you use will adhere.
Use compressed air to blow off any dust from scuffing the surface.
Use rubber gloves to handle the scope after the scope is cleaned as you do not want the oils from your skin / hands on the clean / unpainted surface.
If you have a variable scope you will probably want to tape over the magnification range (and any other portions of the scope such as serial number, manufacturer, etc) so that you will be able to see it after painting.
As you mentioned, very important to get the lens covered. I use a thin foam next to the lens, then a round piece of wood that fits securely in the inside of the the ocular and objective lens such that the wood extends beyond the actual length of the scope.
I then use a wood clamp extended so that it contacts the wood on each end of the scope. Lightly snug the clamp so that you can hold the scope by the clamp when painting without touching the scope. Your other option is to pain one side of the scope while holding the other. After the pained side drys, paint the other side.
If you have any questions just flip me a PM.
Silvertp
