I used 2 strands of lace singles held together throughout . 4 variegated colours and 2 solids. However I think best results will be with 6 - 8 variegated colours. Mine is more cowl size.
Here is my recipe:

1: (AB x1, BC x 1, AC x 1) X5
(x1 is 2 rows or one garter ridge)

  ADD D:
  (DB, AC) X3
  (CD, AB) X3
  (AD, CB) X3  CUT A

2: (BD, BC, CD) X5

   ADD E:
   (EB, CD) X3
   (EC, BD) X3
   (ED, BC) X3    CUT B

Continue adding one and cutting one in this order. When you are through the sequence start with A again untill your scarf is the desired length or your yarn is used up!