I've just started making dolls and I'm not sure what size of those Pigma pens to get. They are called for in a pattern I have but the size isn't given. I don't know what to buy.
For very fine lines you should buy the .005 size. This size is good for drawing outlines of eyes, lips, and other details. For eyeliner a thicker nib could be used, like an .01.
Always store these pens horizontally. The nibs can become plugged with other media (pencil, pen) and if that happens gently draw the nib across a paper towel to clean it.
Best of luck with your doll making.