The craft of using long needles to interweave yarn is called knitting. If you work on your knitting skills, you might be able to make your sister a sweater for her birthday.
Commercial knitting is done on machines — that's how they make most mass-produced sweaters you see in stores. The knitting you might do at home happens more slowly, using knitting needles and skeins of yarn. You can use the word for your project, too: "Where did I put my knitting? I was almost finished with that infinity scarf!" The noun knitting comes from the verb knit and its Old English root meaning "a knot."