Erratum: In the original version, row 5 of the written instructions contained an SSSK where there should have been an SSK. This mistake has been corrected in the current PDF (marked Sept 2012).

Knitted using a möbius cast-on, using a 100-cm circular needle, in one piece.

Both written and charted lace instructions provided.

The sample was knitted with Sweet Clement Smitten. This yarn has now been discontinued and replaced with Smitten II, which is almost identical, so you can use this too.

One skein will make two hairbands.

From the pattern introduction:
Maths and knitting go together like chemistry and cooking — lots of end users don’t think about it and just like to follow the instructions, and you can get fantastic results that way, but if you want to go deeper and truly create something of your own, you have to understand the underlying scientific principles.

The möbius strip is a great example of the combination of knitting and maths. This headband is a 3D illustration of a 2D surface with only one side in 3D space: an infinite track that could turn your mind inside out if you think about it too hard — but also keeps your hair back and your ears warm! The leaf-patterned lace gives it a vernal, organic feel, and the scalloped edges with a picot bind-off are soft, feminine and ever-so-slightly reminiscent of another mathematical wonder: fractals.

So whether it’s to motivate you to do your homework, to tame your hair in the spring breeze or to act as your life-line through a metaphysical maze of numbers, give Escher’s Forest a go and let your geek side out.