Hi! I just did my first zebra cake this weekend. (in my photos) I think you gould do it with either fondant or buttercream. If you are cutting out fondant stripes you can easily lay them on both mediums. I ran out of time and had to pipe them on...i liked how it looked...but I actually don't think I saved anytime 
I recently did my first zebra cake too, you can look at my pictures to see it. I found it was easiest to use fondant. I made white slabs and then cut random pieces out of black fondant, laid them down on the white and took my rolling pin across them to blend them. Then I just laid the slabs onto my buttercream cake.
Good luck, and have fun with it!
I did a zebra print a couple of weeks ago, its in my pic. I suggest laying each stripe close together. I believe they look better that way. Use fondant, its easier. HTH
I've done a few but have my favorite in my photo's. I always use fondant and I just cut the stripes as I'm decorating. I have no pattern I just cut them as I'm putting them on the cake. I love the one in my photos because it has flowers added by request of the customer and I would have never thought of that myself. 
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