I'm trying to recreate this type of effect:
My first guess was the Warp tool in Illustrator (I want this in vector) but I get gaps between the black and white lines so I don't think this is the approach. Any tips?
You could also get more refined or closer to perfect lines if you use BLEND to transition from one line to the next. It might be quicker too because you only need to draw 2 lines possibly.
I would create the top line and then the last line and then select both lines and select on the menu: Object / Blend / Make.
Now you can go to Object / Blend / Blend Options to make changes to how the lines blend.
Once the multiple lines are created then you can do as SaraB says by creating a box around all of the lines and then following steps 6 and 7:
Hope this helps.
I'm sure there are other ways to go about this, but this is how I successfully created this effect in just a few minutes.