Here's a simple way to make a frosty cape for an Elsa costume.  My daughter and I are delighted with how it turned out:  so dainty and elegant!  You'll need one full-size sheet of paper, a can of white spray paint, and fabric.  For my 6-year-old's costume, I bought 1 1/3 yards of 60" wide nylon tulle, pale turquoise color.  Sheer nylon tricot or sheer chiffon would also work, and be less prone to ripping.  (No, ours has not ripped yet.)

Lay out the fabric and fold in half lengthwise, so it's 60" long and half the width you bought.  Cut 4-6" wide scallops along one narrow end.  

Fold the paper and cut out a simple six-pointed star.  Mine was about 4" across.  I reinforced the paper (now my stencil) and helped it lie flat by running 2" wide packing tape in a square around the snowflake.

  Spread the fabric on top of something clean that you don't care if paint gets on.  Darker colors under will make it easier to see the white paint.  In my case, I spread this on the lawn; we have a frosty decoration on it until next mowing!

Spray into your stencil, focusing on the center first, then spraying the points.  Continue until you have all you want, occasionally stopping to wipe excess paint off the stencil (the grass was good for this, too). 

Once the snowflakes are sprayed, 'frost' the edges and scallops of the cape by spraying along the edges.  

With some silver glitter glue or silver sparkle paint, draw on the snowflakes. Add some smaller ones made with only the silver.    Let dry completely.