1. gather your scraps and decide what colors and patterns you like together. you will also need a shirt with the bottom hem, this one has a few holes but no matter you only need the bottom.
2. cut off the bottom hem, straight across.
3. measure this piece to the length you want your boa and knot the ends (about 40")
4. lay out your scraps and cut them into strips, about 1 inch by 7 inches. This will take a long time so be prepared for some aching hands after all the cutting. I highly recommend using a rotary cutter for this vs. scissors.
5. once all of your pieces are cut, you should have about 200 give or take. the book where i got the initial tutorial for this (an awesome book called Generation T) said about 50 or 60 strips and i have found that is bullshit. it is best to cut more than you'll need because this way you can be more mindful of using different colors throughout the scarf. (so you don't run out of a certain color in the middle and then the scarf looks lopsided)
6. start at one end and tie a strip in a basic knot. push it down to the end and tighten.
7. keep knotting strips, varying the colors. Expect this process to take about an hour and half of continuous work. Twist the strips as you push them down to meet the previous knot, this keeps the direction of the tassels varied and fluffy.
9. here is the same technique using only one style and color of shirt (Relay For Life shirts), the only color comes from the print on the shirt itself.
10. two more version of this technique (also for Relay For Life benefit). The one on the left is two strips of white then one pink (pattern). The one on the right is two gray, two white, one pink pattern. I love that one, reminds me of the 1980's.
finally, if you have any scrap pieces left, save them in a box for a future craft or another boa scarf.