Melt butter in water and bring to a boil. Sift flour with salt and add to butter mixture. Heat, stirring, until mixture forms a ball. Remove from heat and add eggs, one at a time, beating well between each addition. Put 1/3 of dough into a pastry bag and pipe through largest hole onto greased baking sheet, forming six S-shaped pastries, each about 3 inches long. These will form necks and heads of swans. Scrape any dough remaining in pastry bag into rest of dough. On a separate, greased baking sheet, form remaining dough into six ovals, drawing dough to a point at one end and rounding other end of oval. These will be bodies of swans. Place baking sheet with oval cream puffs into the oven at 425 degrees and bake for 10 minutes. Place the other baking sheet in oven and continue to bake both batches of dough another 10 minutes. Turn oven down to 350 degrees and bake 5 minutes more, or until "heads" of swans are done. Bake "bodies" 5-10 minutes longer or until done. As baking sheets are removed from oven, remove pastries to racks to cool. Cool completely. Cut an oval from the top of each "body" and cut in half. Scoop any uncooked dough from "bodies". Whip cream until stiff. Beat in powdered sugar, to taste. Put a spoonful of well-drained Mandarin oranges in each "body", dividing equally among the six. Top with equal amounts of whipped cream. Place S-shapes in whipped cream at rounded ends to form neck and head. Place half-ovals in whipped cream behind "necks" to form wings. Serve at once.