I used 1 yard of each fabric.
The top layer is a cute cotton print with teddy bears. The lining is a plain broadcloth, and you could use any cotton fabric such as quilt backing. The interlining is sandwiched between the two fabrics. I used a piece of flannel to give baby a little warmth.
Before starting, make sure you have washed all the fabrics so they are already preshrunk when you lay them out.
Put your three fabrics flat on a table or, if you're limber enough, on a clean floor. Pin all around, leaving a space of about 5" for turning. Stitch, clip the corners at a 45 degree angle. Turn over and stitch the opening closed.