So I gave it a go...
Definitely not as difficult as I once thought, so if you haven't tried, give it a go!
Here's what I used:
Now, I know I said this wasn't a tutorial but I will say this. The eyeliner I used didn't dry very black, more of a dark greyish colour. Which looked ok, but it was difficult to see it on the dark basecoat. However, it went back to it's dark black colour after I applied the topcoat and stayed that way after it dried!
I don't know if that's what happens with every eyeliner, but if it does with yours then that's a great way to fix it!
Happy Saturday, have a great weekend x