Here is a pattern I made up to knit a Hogwarts house scarf for your American Girl Doll! Mine is yellow and black for Hufflepuff but you can change the colors to any house colors you want: Red with gold stripes for gryffindor, Blue with grey stripes for Ravenclaw or Green with grey stripes for Slytherin. It is knit in the round on double-pointed needles. You need to know basic knitting skills and how to knit with double-pointed needles (here is a video if you need help)
You will need:
Worsted weight yarn (size #4) in your chosen colors
Size 8 double-pointed needles
Cast-on 16 stitches (place a stitch marker so you know when the next row starts)
Knit 6 rows in yellow, knit 1 row in black, knit 2 rows yellow, knit 1 row black
(The scarf is being knit inside-out!)
Repeat this pattern until the scarf is the length that you want:
*Knit 7 rows yellow, Knit 1 row black, Knit 2 rows yellow, Knit 1 row black* (end with 7 rows yellow)
My scarf is 33″ long (without the fringe) which is 17 repeats + 7 rows of yellow.
Turn your scarf right-side-out and lay flat. Add fringe to each end: Cut 28 pieces of yellow yarn 5″ long. Use 2 strands together and attach across the bottom edge of the scarf evenly. You should have 7 groups on each end. Trim the ends so it has a nice straight edge. If you don’t know how to add fringe here is a video to help.
My doll’s Hogwarts uniform was made by a friend in a swap on Craftster.
This blog has a bunch of great tutorials for making your doll a uniform and accessories!