idk how long you've been building so please don't be insulted ... this is all purely to try and be helpful ...
The most difficult thing about zippers is getting 2 strand of twisted wire the have an even twist. Unless you twist from both sides, which is obviously difficult, the wires do not twist evenly from end to end. They will always start twisting from the chuck end (or the end that is doing the spinning). So that end will always be a bit tighter of a twist. The remedy for this is to twist until you have the pitch, on the chuck end, just a little wider than you want to end up with. Then flip the stick and twist the other end until it has the same pitch. This is obviously a ridiculous notion considering that a tenth of a mm difference is noticeable when it sets everything off just enough so that the humps don't line up across the coil. The quick fix for this is to twist one side until it breaks and then flip and twist the other till it breaks. But this leads to other problems. If the tension between the 2 wires isn't damn near perfect then your stick will break somewhere in the middle where the slack is, instead of at the chuck end. It also means your stuck with a super tight twist whether you like it or not. Not only does this limit the look of your build to a single outcome, it also affect how the coil functions. Super tight twists tend to be fraught with hot spots. Then comes the wrapping ... Twisted wire is springy as hell. It's already a PITA to get a twisted wire coiled nice and neat. Then you add another one and your trying to keep them lined up to get that zipper affect. Lots of pulling and adjusting and tightening ...
I know that looks like a lot of build up to a hard build. But, in the end it is not difficult. Once, you have a feel for how wire will act in most situations you'll develop intuitions that make all this stuff trivial even if you've never attempted the build before.
Good luck and let us know how it turns out