Chris Palmer demonstrated how to pleat fabric using a technique of pre-stitching it together with thread. More about his work and technique, and the patterns for the folds are all documented in his book Shadow Folds.

Trace pattern of stitch-marks to fabric:

With a needle and thread sew grouped stitch-marks together and tie a square knot. Make sure not to catch any of the fabric when you tie these knots.

When you’re done it helps to look at a photo of the final fold piece you are making, to help you arrange the pleats in the right direction.

You can use an iron to flatten your pattern and enforce the folds:

Links:
Shadow Folds >> http://www.shadowfolds.com/
Chris Palmer demos his work at CNMAT >> http://www.kobakant.at/DIY/?p=3517
Chris Palmer demos his work at Berkeley Rep’s shop >> http://blog.berkeleyrep.org/2012/01/fabric-origami-with-chris-palmer.html