3D fold-up

The fold-up prototype (make -f fold3d.mk) folds the traced pieces along their score lines and glues them edge to edge, the way the paper model is built. Each glued edge gets the gap left between the two sides in the folded model. A small gap means the traced outlines, folds and edge numbers agree in 3D, not only on the sheet.

739 glued edges: 712 close (median gap 0.3 mm).

Gap between the two sides of each glued edge in the folded model (log scale).

Table 1: Glued edges by outcome.

Outcome	Edges
closes	712
does not close	13
let go while building	8
proposed by shape only, not glued	6