Curved creases

Folding paper along curved lines, can create 3D objects made of paper.

Examples:
- "Fascinating and elegant shapes may be folded from a single planar sheet of material without stretching, tearing or cutting, if one incorporates curved folds into the design." [source]


- "Simple Curved Fold" [source]


- A pattern to print and fold a curved container [source]

- Nice, artistic folded paper [source]