I just made a zebra print cake for a bachlorette party this past weekend, and I tried a few different methods. I really didn't want to just stick the stripes on because I wanted it to look like it was part of the white fondant. Anywho, I tried laying the stripes on the white fondant and using my roller to press them into the white....and that didn't really work
. I saw that techniques used somewhere, but I can't recall now. They did it on a much smaller piece....I was trying to cover a 9" cake. I don't know what I was thinking.
So I went to Michaels in search of something to use to cut the stripes, and I ended up buying a clay cutter for $4.99. It's a small instrument (about 6 inches long, and half an inch tall) with a very sharp edge. It is also bedable, so you can cut round corners or staright edges. So I just rolled out a very thin sheet of black fondant, and started cutting at different widths/angles. When I put the stripes onto the white fondant, I tried to curl them a bit so that it wouldn't look so rigid. Everyone at the party loved the cake, I think I could've done a little better.
You can see it under my photos. Just be careful when sticking black fondant onto the white because one mistake will leave you with a nasty, black, cloudy stain.
Best of luck!