Silky Tie Wrap in Bamboo

Here is the Silky Tie Wrap worked in Southwest Trading Company's Bamboo, colorway Bougainville. This is a birthday present for 9-year-old granddaughter Arlyn Danielle.
I knitted this with size US 6 bamboo needles, and the gauge is 5 stitches per inch. It took two 250-yard skeins plus a few yards more.
Now I have almost 3 additional skeins left over, and I'm trying to work out a design for a tank top and/or a skirt, using Iris Schreier's multidirectional techniques. The bamboo yarn gets softer as it is worked, so I think washing it would make it even softer. I'm hunting for a bargain on more STWC bamboo, to make the tank top on the cover of the summer issue of Interweave Knits.