You may be searching for retro squiggles to use in your project.
Have a look at iWork/Pages templates. Musical Poster has a choice of squiggles that create a nice 'retro' effect. Click on the one you like and copy-paste into your project.
If you want to keep it as a separate graphic file, you can extract it from the template by dragging the image icon from the Metrics Inspector.
Click on the graphic element to select it, open the Metrics Inspector, click in the File Info window and drag the icon to the Desktop.