Abstract: Forming thin-wall honeycomb structures using novel extrusion die; method of making the die. The die has feed holes feeding to slots of a primary extrusion grid. A secondary grid is milled between slots of the primary grid, and successive subsequent grids can be provided between previously milled slots (secondary grid, tertiary grid, quaternary grid), and so on. Extrudable material is fed to the die under pressure; the material flows through the feed holes longitudinally to the primary grid, when the material flows to subsequent grid or grids. The material emerges from the die face as a thin-walled honeycomb structure. It is then rigidified to prevent deformation.