Preheat oven to 400 degrees. Heat water and butter to a rolling boil in a saucepan. Stir in flour all at once.
Stir vigorously over low heat until mixture no longer sticks to pan and forms into a ball. Remove from heat.
Beat eggs in thoroughly, one by one. Beat mixture until smooth.
SHAPING THE SWANS:
Bodies:
Spoon cream puff mixture into a pastry bag fitted with a plain 1/2-inch tip. Pipe 8 mounds of dough, the equivalent of a tablespoon onto ungreased baking leaving 3 inches apart.
Flatten each mound slightly with a fork dipped in water. Bake for 15 minutes. Reduce the oven to 350 degrees and continue baking until the choux puffs are golden brown and sound hollow when tapped. Cool on rack.
Heads and Necks:
Increase oven temperature to 400 degrees.
Fit a pastry bag with a small plain tip, pipe S-shaped figure shapes, each about 2 inches long on a baking sheet. Bake for about 8 minutes. Reduce the heat to 350 degrees. Bake for 5 to 6 minutes longer. Cool on rack.
FILLING:
In an electric mixer, whip the cream with sugar and instant vanilla pudding until stiff.
TO ASSEMBLE SWANS:
To make wings, slice the top off each body with a serrated knife. Cut each top in half, lengthwise; set aside.
Pipe the filling into the cavity of each choux puff, finishing about 2 inches above the top of pastry.
Insert two wings, rounded edges down, into the center of each cream filling, so that they form a V-shape. Insert the S-shaped neck into the cream.