you'll need a pretty strong linear actuator to be able to pull your skin enough to have the desired effect. I remembered that CD players had nice worm gear motors in them to move the laser back and forth across the CD, so I looked through my junk pile and found an old CD walkman. I tore it apart using screwdrivers etc. and took out the linear actuator assembly, this will look different depending on the CD player but it's easy to identify if you know what you're looking for. I didn't take photos of this part so you'll have to look at the photos I got from wikipedia (http://en.wikipedia.org/wiki/CD_Walkman, http://en.wikipedia.org/wiki/Compact_Disc_player).
= The first photo shows a portable CD player, you could also take apart a non-portable CD player but those are usually a little harder to take apart.
= The second photo show the inside of a CD player. The black region on the green board on the left is what you're after, it has all the necessary motors and gears attached.
= The third photo shows this same mechanism from the underside, showing the motors and gears. You do not need to disassemble this mechanism, you will use it as is. All you need to cut are the wires leading to the rectangular motor (as noted on the photo).
Looking at the third photo: We'll be interfacing with the rectangular motor which is connected to the worm gear which is connected to the laser lense. The laser lense gets moved linearly, up and down along the worm gear. A 'worm gear' is the best way to allow low torque motors (such as the small rectangular one in the photo) to be used in high torque applications (like this one), but some cheaper CD players won't use worm gears. These alternate gear configurations will also work ok for this application.