How would I do this? Tattoo design

Hey All,

Ive been trying to make a brush or find one that would produce brush stokes similar to these gradient waves. Not the whole thing but just individual gradient wave shapes. 

https://i.pinimg.com/originals/e7/7b/d0/e77bd0257dcff18ed91f3a1ed53ed3a0.jpg

Ive tried creating a gradient making it a brush and adjusting spacing and brush properties but cant achive what I want. If anyone has any tips I would really appreciate it!

Thank you