Materials required: a ball of yarn (various colours could be sold, or perhaps the PC would have to dye the yarn by hand), knitting needles or a loom.
There could also be different kinds of yarn, such as alpaca, wool, etc.
Small/easy items would require one ball of yarn. Examples of this would include socks, handkerchiefs, mittens, small pouches. Would require only basic knowledge of the trade.
Medium size/difficulty items would require two. Examples of this would be sleeves, handbags, money pouches, etc. Would require novice or above of the trade to do well.
Large size/difficulty items would require three. Examples of this would be tunics, breeches, blankets, packs. Would require journeyman or above of the trade to do well.
Maybe there would be items that would require four balls of yarn and master or above, but I can't think of them at present.
In effect it would be a fairly useless trade, but a fun one and good for flavor and RP.
Thoughts and comments?
