If you chop full length feathers, keep the "extras" from the chopper.
I read about these flus from local MD bowhunter Rob Davis's book....FAFFY (good read by the way).
He had issues with squirrels ducking out of the way because of the noise and slow speed of spiral and traditional flu flus. This design goes very fast to about 15 -20 yards then starts to slow dramatically. I still use the regular kind for shooting aerials but these are "murder" on squirrel.
straight 4 fletched. 3 x 5/8" sections 4 inches in length total. The sections are so small you do not need a fletching clamp to make them, just a clothes pin to keep the shaft from rolling.
here is also his tip for the ends, 38 shell with banding steel: