If you are looking to create some of your own Op Art and aren’t sure where to start, then these Op Art Photoshop brushes from Spiral Pixel Design might be a good place to start.
There are 25 Op Art (and geometric) brushes created by Jo (from josweb.co.uk) in the package and they are completely free to use in both personal and commercial projects.
Op Art Photoshop brushes by Olly