I need to cover a few pins on my rigging.
I don't use any tape or coverings on my boat. Everything is bare for easy inspection and to minimize crevice corrosion. Looks good and less stuff to buy. No plastic covers on shrouds or lifelines or turnbuckle boots.
Cotter pins in things like toggle jaws should be cut short enough not to project beyond the fitting. Leave them just long enough to spread the ends about 20 degrees. It doesn't look as secure as bending the long ends all the way around but they are actually more likely to stay in. The sharp bends curving them back on themselves weaken the metal and they are more likely to break and then fall out. When you go to remove a cotter pin done this way, you'll see that it's perfectly secure.
If a cotter pin is in a place where a line in constantly running over it, you may have to tape it to avoid chafe. Turning the clevis around will often solve the problem. I don't have any pins taped on my boat and haven't found a place where it is needed.
A neater way to secure turnbuckles is to go to a welding supply store and buy a lifetime supply bundle of S.S. welding rod which is about 1/16" diameter. After the turnbuckles are adjusted, bend a piece of the rod into a long "[" shape, that fits the spacing of the pin holes. Insert in the turnbuckle and bend the ends up and around into the turnbuckle body. Very neat, unobtrusive, and non-fouling of sheets.
The only place I have any tape on my boat is on the plastic spreader boots and I'm going to use white waxed sail twine seizings this year because an end of the tape has come loose two years in a row making an Irish pendant that drives me nuts when I look at it because I can't get up there to do anything about it.