I still am fascinated with shells and spirals and Tomoko Fuse's shell/nautilus (am not really sure of the difference between the two!) from her book on spirals (Let's Fold Spirals) is a good place to start.
The spiral sea shell A which I tried, turned out to be an interesting origami to fold. The diagram is clear and makes the folding quite easy. The shell is quite realistic if done in the right colours.
Model Details:
Model: Shell/Nautilus
Creator: Tomoko Fuse
Book: Let's Fold Spirals
Author: Tomoko Fuse
Language: Japanese
Paper Ratio: Square
Paper Size: 7 inches
Posts
