Skill

Paper folding

A sheet is folded, punched, then imagined unfolded. The holes you see are mirrors of the punch across every crease, in reverse order.

Undo, do not guess symmetry

Start from the last fold. Unfold it, and copy every hole across that crease. Repeat until the paper is full size. If a punch went through three layers, it becomes three holes.

Foldmetry includes generated fold sequences and a clearly attributed MentalBlackboard animation subset under CC BY 4.0.

Unfold a sheet in the app

Worked unfold

  1. List the folds from last to first.
  2. For a left-to-right fold, mirror every hole across the vertical crease.
  3. For a top-to-bottom fold, mirror across the horizontal crease.
  4. Keep hole count consistent with layers. A distractor that drops a hole is wrong.