Adding a zig zag

[Shells]

I'm making a beanie hat for a friend using half double crochet. He wants the brim to be a zig zag pattern. Any ideas on how to do this?

[Granny Square]

Welcome to the 'ville!  Does he want a zig zag color stripe, or a raised (textured) stripe?  A saw-tooth edge to the hat? something else?  

 

 

[Granny Square]

A search on free hats and 'zig zag' doesn't yield much, do any of these look close to what he's thinking of?  I didn't limit it to looking for HDC, I think that is going to really limit the possibilities of existing patterns. (link goes to Ravelry, you don't have to be a member to look at the pattern page, but you do to download the pattern if it is hosted on Ravelry.  (This is a database, only members' patterns are hosted there, there may be links to blogs and yarn sites etc. for free patterns, but others may be in physical books or magazines that you'd have to find an original copy of).

Another search on 'ripple' attribute.