I did this in GIMP1, I also used the Painting filter in the G’MIC2 plug-in for GIMP [Filters->Artistic->Painting] to create the black outline. Then using the pencil tool, I drew various tangle patterns.
Until next time…
1 GIMP is Open Source software that is available for all platforms (Linux, Mac, and Windows), it is a photo editor that does many (if not all) of the things you can do in Photoshop. You can download it for free here. The GIMP online manual can be found here.
Like Wilber? You can get him here.
2 G’MIC Plug-in for GIMP is a plug-in that has a ton of filters, you can download it here.