Tools and materials:
Velvet or other soft, cushiony fabric (I used a long piece 6 1/2 x 54 inches, folded in half)
Craft knife and/or scissors
Hot glue and glue gun
Cut away the lid to the box, if necessary, and wrap in the paper, leaving the top open. Secure with glue or tape.
With your craft knife and ruler, begin by cutting about 10 pieces of foam core into rectangles that fit the width and depth of your box. You may need more or less depending on the size of your box. For mine, I used 11 rectangles 2 1/4 inches by ___ inches.
Taking your long strip of velvet, glue one end onto the inside of the box. Apply glue to one of the foam core rectangles and press against the velvet. Fold the the fabric about halfway down the foam core, and glue in place. Continue folding, gluing, and adding additional rectangles of foam core.
Once the box is filled, trim and tuck the end of the fabric and secure with glue.