I will have to look, I know all three of my build threads for the Nike Smoke, Nike Cajun, and the Nike Hercules should have pictures, I will try and link them in a bit.
Okay
Pic 1-3: Nike Smoke Fins, cores, core with center skin and ribs, and finished fins two with paper. The basswood ribs are visible in picture 2 on each side of the center skin.
Pic 4 and 5 Nike-Cajun fins with basswood center rib and balsa side skins.
Pic 6-8 Nike Hercules Sustainer Fins basswood rib along bottom, plywood core and balsa built up skin (profile was formed with Great Planes Razor Plane and sanding), the rear triangle portion was made from posterboard.
Pics 9-10 Nike Hercules Booster Fins, same construction method as others except basswood ribs were along the root and tip edges, the softer balsa was in the center skins and leading and trailing edges (not yet installed in pic 9), these profiles were sanded entirely using the 11" Great Planes Easy Touch Sander (would have been nice though to have the 22").
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Edit by pre-sanding the center rib on the Nike Cajun fins it was easy to profile the taper from root to tip so that once the skins were added it was just a matter of sanding to match the rib in the center and to the edge of the plywood core. The plywood cores are leave a leading edge thicker than true scale but the fins are a bit less prone to damage having thicker edges and the ply cores are much stronger. The plywood is either 3mm Baltic Birch (which I get from wholesaler in 5'x5' sheets) or its Midwest 1/8" bought at Hobby Lobby, Micheal's, or Craft Warehouse.