I made this for a talk, entitled Wears the Maths, which I gave at Mathsjam 2012. I also made a Klein bottle hat with the same unknown yarn.

The waistcoat was based on Elizabeth Zimmermann’s Mobius vest but I wanted to make it more mathematical. It is entirely without seams or visible joins, making it a truly one-sided, one-edged, piece of knitting.

I used the front shaping as recommended in Knitting Around but only as far down as the bottom of the armholes. I also added a couple of extra stitches to the width of the fronts and some short row shaping at the lower back.

I curved the edges at the front as I wanted the i-cord to be a continuous curved line without any corners. This was probably a mistake as it made the corners curl up a bit.

On the back view you will see a button at the centre of the neck. This has three purposes:

1. It covers the only join in the entire garment
2. It makes it easy to see which way round to put the waistcoat on. It can be worn in two different ways but it is helpful to be able to see which is which.
3. It enables someone to trace their way round the edge and know when they have got back to the beginning.

A fastening would be useful but I didn’t have time for that as I finished it on the night before Mathsjam.