This afghan was inspired by a shape of constant width, which is a mathematical curiosity with a lot of practical uses.

The construction is deceptively simple. There are just a couple of rules to memorise and, once you have made the first shape, you won’t even need to refer to the pattern again. It is made with one colour at a time and each new colour is knitted onto existing stitches so there is no picking up and no stitching to be done. (There are quite a lot of ends to darn in because of the number of colour changes.)

It can be made in any yarn and if you want to change the size, to suit your yarn, or for some other reason, the pattern gives you one simple rule for doing that.

It could be coloured in a variety of different ways. One of the photos gives you some ideas. The pattern includes a colouring-in sheet for you to plan your own design.

The design is based on sound mathematics but the construction relies on the flexible nature of knitting to make the shapes fit together. It will need a little blocking to make it lie flat. For this reason, we suggest using a yarn with some wool content so that it can be easily flattened.

The afghan shown in the main photo was made in acrylic yarn.It used

• 700 metres (770 yards) in each of two main colours,
• 300 metres (330 yards0 in each of two contrasts
• 300 metres (330 yards) for the border

It can be made on long straight needles but we recommend circular needles instead because it has a tendency to twist and turn, especially at the start.

If you are an absolute perfectionist this may not be the pattern for you. Take a look at the close-ups where you may notice that some of the colour changes are perhaps not as smooth as you might like.

You can read about the development of the design on the Woolly Thoughts web site or in this thread.