Something like this would look really cool with a little color
How to Create Parabolic Curves Using Straight Lines. tutorial for string art - bit more advanced!
"A Fan of a Fan" 8x10 print by Virginia Kraljevic. Etsy shop specializes in B/W pen & ink drawings that are abstract and quirky.
folding sketches- Love how this composition is simply made but complex visually.
Op Art cube
PEN & GRAVY, DOODLE: aka jamie; aka a "doodler". found via @binx
patternbase: Alexander Ross source: contemporary art links