So once you've made your yarn, your left with this:
Use it to make sweeper covers! You will get 2 of them from your leftovers.
Fold it in half, and remove the sleeves...
...and the neck.
Next, measure your duster/sweeper. Mine is 10" long by about 4" wide. I added 2" to each side to be able to wrap the t-shirt material up and over, and to then be able to tuck it into the little holes.
I cut mine 6" wide...
...by 14" long.
Also, there were a few pieces (little strips from hem and leftovers of main rectangles, collar) that I could not use. I went ahead and pitched these in the trash. I left the sleeves whole, and can use them for cleaning mirrors and windows instead of paper towels (I use one wet, and then go over everything with the other dry).