CNC engraving is used to route a pattern through the veneer layers of plywood.
This type of decoration is achieved by setting a V-cutter to cut various depths. By doing so the V-cutter routes different line widths.
“Un-Upholstered chair” by Courtney Skott 2004 (above) using one line width.
“Shelfy” by The Summer Office 2006 (below) using three line widths.
Further examples of both projects (below)