Apply a small amount of glue to foam cone, then wrap cone evenly with A. Continue applying small amounts of glue, then wrapping with A until cone is completely covered. Allow to dry.
In same way, cover foam ball with B.
Cut 2 lengths of A and 1 length of B, each about 2 yards (1.5 meters) long. Fold strands in half and knot about 4 in. (10 cm) from fold to form a loop. Secure loop around doorknob. Twist other end tightly until yarn begins to twist back on itself. Release loop from doorknob. Bring ends together and let cord twist on itself, smoothing to even the twist. Knot ends.
Glue Cord around wrapped cone. Glue ball to top of cone.