(A terrific tutorial from the Just Bento forum!)
Furoshiki are a traditional Japanese wrapping cloth. They come in lots of sizes and are used for wrapping gifts, treasures, and bentos. As a bento wrapping they are extremely handy, because in addition to keeping your bento together (if you don’t have a belt), and mopping up any small spills of wet stuff that may escape your box on the way to work, they transform into a small tablecloth or napkin when you unwrap your lunch.
Furoshiki come in various fabrics, including silk, but for wrapping my lunch I like cotton. It’s absorbent (for mopping up those wee spills) and I can chuck it in the washing machine when I get home from work. It doesn’t need any special care.
I get fabric for making furoshiki from the quilting supplies shop; they sell 100% cotton fabric in 50cm x 50cm (20” x 20”) squares called fat quarters that are a perfect size for bento furoshiki. They also have amazing patterns! [Note: Our fat quarters are a quarter of a metre. In America they are quarter of a yard, so will be the same width but an inch and a half or so shorter.]
Fold your fabric diagonally and trim it up so its sides are straight. Traditionally furoshiki are slightly rectangular rather than square, so don’t fret about the sides being the same length. You need to cut off a piece about 4 cm (1.5”) wide (or 3 x the width of some elastic you have) from one side to make the matching belt.