One cut, six arms

Today I cut my first snowflake on the Duo. The paper starts as a round sheet, folded down to a thin wedge twelve layers thick. I drag a finger across it, and the scissors sound, and nothing seems to have happened. Then I open the phone. The hinge is the unfolding: the wedge swings out, then again, then once more, and a flake with six arms lies flat on the felt.

It works because of an old fact. Erik Demaine, Martin Demaine and Anna Lubiw proved that any shape made of straight lines can come from a folded sheet with one straight cut. A snowflake is the friendly case. Wilson Bentley spent his life photographing the real ones.

Elsewhere, the first spread of Hill Country Night has bats pouring out of the fold.

Thanks

• Demaine, Demaine and Lubiw, for the fold-and-cut theorem.
• Wilson Bentley's Snow Crystals, and the Jericho Historical Society, which keeps his photographs.
• Bat plates from Audubon, through the Biodiversity Heritage Library. The bats' friends: Bat Conservation International.