{"L1_core": {"domain": "materials", "category": "plastic_tube", "entity_type": "material"}, "L5_metadata": {"updated": "2026-01-02", "version": "2.0"}, "L2_materials": {"types": {"cast": "premium_better_optics", "extruded": "economical_wide_tolerances"}, "material": "PMMA", "standards": ["ISO 7823", "ASTM D788"], "dimensions": {"OD_mm": [10, 500], "lengths_m": [1, 2, 3], "wall_thickness_mm": [2, 10]}, "properties": {"density_g_cm3": 1.18, "service_temp_C": [-40, 80], "refractive_index": 1.49, "light_transmission_pct": 92, "impact_resistance_vs_glass": 10}, "applications": ["lighting_diffusers", "display", "aquariums", "food_industry"]}}