To be frank, the shape of this stamp isn’t going to work on every eye shape out there. I only use it every now and then because I have hooded eyes and need a really specific shape to prevent my eyeliner from completely disappearing into my creases. That said, you can use it in a few different ways depending on what you need.
On my really lazy days (like, not even bothering to brush my hair lazy), I lightly press the stamp to my outer corners and use that as a template while I draw the rest on with the regular felt-tip side. An even quicker way to use the stamp is to press it down where you want your wing to end and drag it all the way inwards. Either way, you’ll probably need the pen side to perfect the edges and clean up the lines.
Even if you don’t use the stamp that often, the eyeliner will be wholly worth it thanks to that other felt pen side. It’s thick, dramatically tapered, and really stiff so it grants you maximum control as opposed to flimsier, thinner pens that bend and slip (which aren’t always conducive to makeup on the go).