What are good markers for use on the skin?

What do you mean by long lasting? Like, to the end of an event? Or days? Because the two are going to require different media. I used http://www.montana-cans.com/products/Marker_Inks/Montana_ACRYLIC_Marker_Paint/Montana_ACRYLIC_Marker_Fine_2mm/169 in darker colours on skin for some art photography and they worked SO beautifully. (Send me a message if you want to see some photos of how the paint interacted with the skin on my model.) Being acrylic it's pretty inert on the skin, and it washes off cleanly, even with super dark, saturated colours (the white wasn't quite opaque enough though, so you may need to experiment with colours). These markers also come in bigger widths, like everything from chunky sharpie-sized, all the way up to 4 inches across or so. The only issue is they occasionally need a pump against a surface, but that could be part of the machine? If you're looking for longer lasting you'll probably want an archival pigment ink of some kind. I know I've doodled on myself with http://sakuraofamerica.shptron.com/p/pigma-micron-01-fine-point-pen-25-mm-black-ink/marker?pp=25&pp=25 and although it takes a little bit to dry (like maybe, 10-15 minutes?) it lasts for days, even through showers if you don't rub at it. Feel free to memail me if you want to kick around ideas. Ink and paint on skin is my jam.

I used copic markers to draw a tattoo on myself for a costume party one year. (Ana Matronic costume, holla!) They worked really well for details, and lasted through the party and probably longer or required some serious scrubbing in the shower to get off.