Step 4: Stencil
You can create this stencil yourself or just download mine.
Scale the stencil so the first row starts in the middle of your wave
and the first and last column match the beginning and end of your wave.
This stencil has 80 columns. If you use a material of 1mm thickness, your necklace will have a lentgh of 8cm. Easy math. So calculate how thick your material is, how long you want your necklace to be and start calculating how mani columns you'll have to use.