Fold the 1/2″ seams in opposite directions (one over the batting and one underneath itself) and iron flat.
Turn each piece inside out.
Pin the opposite-colored seams together.
Slip-stitch the opposite-colored seams together.
Cut 16 strips in one of the fabric colors to 1″ x 23″. These will be the ties that attach each crib bumper pads piece to the crib.
Sew each tie with the smallest seam your sewing machine will allow.
Stitch ties onto the corners of each of the crib bumper pads' pieces.