I am planning on doing a cake with chevrons on it. For those who have done this type of cake, How do you determine the width and length of these? What type of problems do I need to watch for? Can this be done on buttercream?

maybe wrap a sheet of paper around your finished cake and then determine the zig zag pattern on that? Then you can cut out the zig zag and trace it onto your fondant and roll it up, then roll it out on your cake? SOrry - I can picture what I mean in my head but it is hard to explain!