Andrew Buckle / graphicxtras

You can combine a pattern overlay in Photoshop by selecting a shape layer etc and then adding a pattern overlay via the layer styles menu and then by going to the layer menu and convert smart object and then going back to the layer menu and layer styles and pattern overlay. Change the blending modes etc and re-position the different patterns. You can repeat this over and over.  Some have more than two pattern overlays and some also mix a few effects to smear the results. Here are a few examples below using the patterns from graphicxtras.com

http://www.graphicxtras.com/contours.htm 1000s and 1000s of great designs can be created using the artworks in the sets - they are for use in Photoshop CC CS6 CS5 CS4 CS3 CS2 CS1 etc as well as standalone 6, 7, 8, 9, etc all the way up to the current version along with Photoshop Elements. All for commercial use, all extended license (the images show only a small sampler of the artworks in the set being use with a style added to the artwork)