A method of forming a structural honeycomb includes cutting and folding a substrate sheet according to predetermined cutting and folding patterns and fold angles that cause the sheet to form a honeycomb having cells that each have at least one face abutting, or nearly abutting, the face of another cell. The honeycomb is then stabilized by joining abutting, or nearly abutting, faces to hold the honeycomb together. The honeycomb may have a prespecified three-dimensional shape. The folding pattern may include corrugation, canted corrugation, or zig-zag folds. Joining may employ fixed and/or reversible joinery, including slotted cross section, tabbed strip, angled strip, integral skin, sewn, or laced. At least some folds may be partially-closed to create bends and twists in the honeycomb structure. Some surfaces of the honeycomb may be covered with a skin or face sheet. The substrate sheet may have flexible electronic traces.

In one example embodiment, a film includes a coextruded structure having both an extruded ribbed skin layer that includes a plurality of ribs, and a core layer. The ribs are spaced apart by a web that is integral with the ribs. The film also includes a coloring agent that is substantially more apparent in the ribs than in the web, such that a contrast in color and/or color intensity between the ribs and the web is visible.

In one example embodiment, a film includes a coextruded structure having both an extruded ribbed skin layer that includes a plurality of ribs, and a core layer. The ribs are spaced apart by a web that is integral with the ribs. The film also includes a voiding agent in the ribs of the skin layer.

In one example embodiment, a film includes a coextruded structure having both an extruded ribbed skin layer that includes a plurality of ribs, and a core layer. The ribs are spaced apart by a web that is integral with the ribs. The film also includes a coloring agent that is substantially more apparent in the ribs than in the web, such that a contrast in color and/or color intensity between the ribs and the web is visible.