Self-Developed Vintage, Metal Hides Edge — Retro Metal Lunch Box, with "self-developed design, metal texture, practical innovation" as its core positioning, breaks the reproduction limitations of traditional vintage lunch boxes, integrates self-developed craftsmanship with vintage aesthetics, based on diverse scenarios such as daily use, outdoor travel, vintage collection and gift giving, balancing vintage appearance and modern practical needs, accurately controlling every self-developed parameter, creating a vintage metal lunch box with original design sense, metal texture and convenient performance. It is suitable for vintage enthusiasts, urban office workers, outdoor enthusiasts and people pursuing a delicate life. It not only meets the demand for vintage aesthetics, but also fits the convenient storage needs of modern life. With self-developed craftsmanship, it breaks through the pain points of traditional metal lunch boxes, becoming a preferred product with both originality and practicality in the field of vintage metal stationery. We adhere to the core concept of "self-development for characteristics, details for quality", relying on the independent R&D team to optimize metal material ratio, structural design and process details. From material, size, structure to safety and durability, every parameter has been independently R&D calculated and repeatedly tested, not only restoring the classic style of vintage metal, but also integrating the convenient characteristics of modern use, perfectly integrating vintage charm with self-development strength, and showing the aesthetics of original vintage life.

　　Core Size Parameters: Self-Developed Adaptation, Balancing Appearance and Portability. Breaking the size limitations of traditional vintage metal lunch boxes, combining the usage habits and storage needs of modern people, independently R&D and design size parameters with an error of ±0.1cm, ensuring that each product not only retains the vintage version ratio, but also adapts to modern daily use scenarios. The overall size is divided into three self-developed versions, accurately matching the needs of different groups of people: Classic Self-Developed Version (suitable for daily commuting + light collection): 21cm in length × 11.5cm in width × 6.2cm in height, overall weight 400-430g, capacity about 1491ml, suitable for single-person lunch storage, can be easily put into commuter backpacks and handbags. The self-developed ratio design balances vintage sense of weight and portability, reproduces the classic outline of vintage metal lunch boxes, and optimizes the size to adapt to modern backpack sizes. The corners adopt self-developed rounded arc design, restoring the vintage texture while improving carrying comfort; Collection Self-Developed Version (suitable for vintage collection + scene decoration): 23cm in length × 12.5cm in width × 6.8cm in height, weight 460-490g, capacity about 1942ml. The self-developed version integrates the classic elements of vintage metal lunch boxes with modern design aesthetics. The size ratio is independently calculated, suitable for collection display and vintage scene decoration. The corner details reproduce the classic lines of vintage metal utensils, showing collection value and self-developed design sense; Mini Self-Developed Version (suitable for outdoor portability + desktop decoration): 15.5cm in length × 9.5cm in width × 5.2cm in height, weight 310-330g, capacity about 786ml, small and exquisite. The self-developed mini version is suitable for short-distance travel and snack storage, and can also be used as a vintage desktop ornament, balancing practicality and decorativeness, suitable for desktop, window and other scene placement. In addition, the lid thickness is 0.42cm, the box body thickness is 0.38cm, and the bottom thickness is 0.46cm. The self-developed metal thickening process is adopted to balance metal texture and structural stability. The corner radius is 0.75cm, which is processed by self-developed refined polishing technology, not only having the tough texture of vintage metal, but also avoiding sharp corners, adapting to the safety needs of daily use.

　　Material Parameters: Self-Developed Ratio, Balancing Texture and Durability. Breaking the limitations of traditional vintage metal materials, independently R&D metal material ratio scheme, selecting high-quality alloy materials, strictly controlling material parameters, not only meeting modern food contact safety standards, but also restoring the warm texture of vintage metal. All materials meet the national food contact metal material standard (GB 4806.9-2016) and the EU food contact material safety standard (EC 1935/2004), with no harmful residues and no odor, suitable for long-term use and collection. The main body of the box is made of self-developed high-toughness metal alloy, with independently proportioned tin, iron and stainless steel components, including tin content ≥45%, iron content ≤40%, and stainless steel content ≥15%. The material density is 6.8g/cm³, tensile strength ≥18MPa, flexural strength ≥32MPa, and Shore hardness 58-68 degrees. It has good ductility, wear resistance and corrosion resistance, reproduces the warm touch of vintage metal, and avoids the pain points of traditional metal being prone to rust and deformation. The service life is ≥40 months, and natural vintage patina can be formed after long-term use, showing vintage charm; It also has good moisture-proof and anti-oxidation performance. The self-developed surface anti-oxidation coating process can effectively isolate air and moisture, protect the food inside the box from dampness and flavor mixing, adapt to the storage needs of lunch, snacks and other ingredients, and prevent metal oxidation and discoloration, retaining the vintage metal texture. The box lid is made of the same self-developed metal alloy, with a thickness of 0.42cm, compressive strength ≥22MPa, not easy to dent or deform. The self-developed closing fit design ensures tight closing, balancing sealing and vintage texture. The internal partition is made of food-grade self-developed metal material, with a thickness of 0.32cm, which can be freely disassembled. The height of the partition is 4.6cm, with a self-developed adjustable design, which can flexibly divide the storage space to adapt to the classified storage of staple food, dishes and soup. The partition load-bearing is ≥850g, not easy to bend or break, and fits the overall vintage tone, perfectly integrating with the box body material. In addition, the vintage lines on the box body adopt self-developed chiseling + wire drawing process without additional ink printing, avoiding harmful volatile substances, balancing vintage texture and use safety. At the same time, the metal material can be 100% recycled, environmentally friendly and durable, conforming to the modern green life concept, showing the environmental value of self-developed products.

　　Structural Parameters: Self-Developed Optimization, Convenient, Practical and Textured. Relying on the classic structure of traditional vintage metal lunch boxes, combined with modern usage habits, independently R&D and optimize structural parameters, create a self-developed structural design of "vintage version + modern convenience". Every structural parameter balances vintage charm and modern use convenience, restores the structural beauty of traditional metal lunch boxes, and solves the use pain points of traditional products. The opening and closing structure adopts a self-developed buckle design, integrating the classic shape of vintage metal buckles with modern convenient opening and closing needs. The buckle thickness is 0.32cm, width is 2.1cm, load-bearing ≥1600g, opening and closing smoothly. It not only retains the vintage opening and closing feel, but also ensures tight closing, with a gap of ≤0.1cm after closing, which can effectively prevent soup leakage, adapting to daily carrying and outdoor use; The surface of the buckle adopts self-developed frosted polishing technology without redundant decoration, with a warm touch, fitting the vintage tone, and avoiding slipping when opening and closing, improving the convenience of use, solving the pain points of traditional metal buckles being prone to looseness and rust. Internal structural parameters: The classic self-developed version is equipped with 1 main storage compartment + 1 small soup compartment, the main storage compartment size is 20cm×10.5cm×5.7cm, and the soup compartment size is 8.2cm×6.2cm×5.2cm. The self-developed partition design can classify and store staple food and soup to avoid flavor mixing, and the soup compartment adopts self-developed leak-proof design to improve practicality; The collection self-developed version is equipped with 1 main storage compartment + 1 small storage grid + 1 tableware compartment, the main storage compartment size is 22cm×11.5cm×6.3cm, the small storage grid size is 6.2cm×5.2cm×5.8cm, and the tableware compartment can place supporting self-developed vintage metal tableware, balancing storage practicality and vintage integrity; The mini self-developed version is equipped with 1 main storage compartment, size 14.5cm×8.5cm×4.7cm, suitable for small food storage, simple and practical. The self-developed lightweight structural design improves carrying convenience. The bottom structure adopts a self-developed vintage anti-slip design, with 4 silica gel anti-slip pads, the diameter of the anti-slip pad is 1.25cm, thickness is 0.26cm, Shore hardness 52-62 degrees, anti-slip coefficient ≥0.48, which can effectively prevent the lunch box from sliding on the desktop, avoid falling and damage, and at the same time not damage the overall vintage version; The bottom adopts self-developed embossing process, reproducing the bottom lines of vintage metal utensils, increasing the texture and improving the wear resistance of the bottom, adapting to daily placement and carrying, solving the problem that the bottom of traditional metal lunch boxes is easy to wear and slip.

　　Safety Parameters: Self-Developed Control, Protecting Use Safety. Focusing on daily use and collection needs, independently R&D safety control standards, strictly standardize various safety parameters. All safety parameters meet modern food contact safety standards, and at the same time, combined with the characteristics of vintage metal materials, comprehensively ensure use safety, eliminate potential safety hazards, and balance practicality and collectibility. Material safety parameters: No odor (odor level ≤1), no harmful volatile substances, no excessive heavy metals, lead content ≤0.0008mg/kg, cadmium content ≤0.0004mg/kg. The self-developed metal ratio scheme ensures that the material is non-toxic and harmless, meets food contact safety standards, and is harmless to human body when in long-term contact with food, so it can be used with confidence; The metal alloy is treated with self-developed chrome-free passivation, no harmful residues, avoiding harmful substances generated during oxidation, and at the same time protecting the metal surface texture, extending the service life, solving the safety hazard of traditional metal being prone to oxidation and rust. Corner safety parameters: All corners are polished through 7 self-developed refined polishing processes, with a polishing accuracy of ≤0.008mm, a corner radius of 0.75cm, no burrs, no sharp corners, smooth and warm surface, fitting the polishing standard of vintage metal utensils, which can effectively avoid scratching hands, adapting to the safety needs of daily use. Temperature resistance safety parameters: The material temperature resistance range is -8℃-75℃, which can adapt to daily indoor and outdoor temperature changes, avoid high-temperature deformation and low-temperature brittleness, and adapt to use in different environments; It also has good impact resistance, no damage or deformation when dropped from a height of 1.6m, can withstand daily dropping and collision, eliminate the potential safety hazard of sharp corners after damage, and protect the vintage version from damage. The self-developed material ratio improves the impact resistance of the product. Load-bearing safety parameters: The overall load-bearing of the box body is ≥8.5kg, the lid load-bearing is ≥3.2kg, the partition load-bearing is ≥850g, and the buckle load-bearing is ≥1600g, which can withstand daily extrusion and stacking, not easy to deform or dent, ensuring the safety and durability of the product during use, and at the same time protecting the vintage texture from damage. The self-developed structural design improves the load-bearing performance of the product.

　　Durability and Adaptability Parameters: Self-Developed Upgrade, Long-Term Durable and Adaptable to Diverse Scenarios. Balancing vintage collection and modern daily use, independently R&D durability parameter standards to ensure that the product can be used and collected for a long time, and at the same time adapt to diverse scenarios, improving product practicality and adaptability, breaking through the durability pain points of traditional vintage metal lunch boxes. Durability parameters: Service life ≥40 months, under normal use, the box body is free of damage, deformation and obvious oxidation marks, and can form a natural patina after long-term use, improving the vintage texture; The number of opening and closing times is ≥2200, the buckle is free of looseness and breakage, and the opening and closing are smooth, retaining the vintage opening and closing feel. The self-developed buckle structure solves the problem that traditional metal buckles are prone to looseness and breakage; The number of friction resistance times is ≥850, the surface has no obvious scratches, can withstand daily friction use, and the self-developed surface coating process can ensure that the vintage lines are clear for a long time, avoiding fading and falling off; Waterproof performance: No water seepage after soaking for 70 minutes, which can effectively prevent rainwater and water stains from seeping in, protect the food inside the box from dampness, and adapt to outdoor picnics, short-distance trips and other scenarios. The self-developed sealing design improves waterproof performance. Adaptability parameters: Suitable for vintage enthusiasts, urban office workers, outdoor enthusiasts and people pursuing a delicate life, covering diverse scenarios such as daily lunch storage, outdoor picnics, vintage collection, scene decoration and gift giving; It can store various ingredients such as staple food, dishes, soup and snacks, adapting to the light use needs of single and double people; Suitable for vintage scene decoration, can be used as a vintage ornament and window display, showing vintage style and self-developed design sense; Suitable for bulk purchase scenarios, the minimum order quantity for bulk purchase is ≥25 pieces, which can adapt to the bulk purchase needs of vintage cultural and creative stores, gift stores, enterprise customization, etc. The size error of bulk purchase is ≤±0.1cm, ensuring product consistency. In addition, the product can withstand daily cleaning, can be directly wiped with a soft cloth, no residue and no scratches after wiping, avoiding damage to the metal surface texture with hard cleaning tools, adapting to daily cleaning needs, balancing practicality and collectibility. The self-developed surface process is easy to clean and take care of.

　　Additional Parameters: Self-Developed Details, Improve Vintage Experience. In addition to the core parameters, independently R&D and optimize various additional parameters, balancing vintage texture and detailed experience, integrating convenient details of modern use, making the product more vintage charm and collection value, and improving modern use comfort, showing self-development strength. Vintage pattern parameters: The box body adopts self-developed chiseling + wire drawing process, the pattern depth is 0.12-0.16cm, the pattern is clear, no blurring, no falling off. The self-developed vintage pattern design integrates traditional vintage elements with modern minimalist aesthetics, not only having the charm of classic vintage patterns, but also having modern design sense. The chiseling accuracy is ≥320dpi, balancing vintage texture and craft beauty. The pattern of each product is carefully polished by hand, showing ingenuity; The plain surface is treated with self-developed matte frosting, with soft luster and no dazzling reflection, fitting the vintage tone, and avoiding fingerprint residue, easy to clean, solving the problem that the traditional metal surface is prone to fingerprint and difficult to clean. Weight parameters: The overall weight is controlled at 310-490g, self-developed lightweight design, balancing the heavy texture of vintage metal and portability, not only retaining the metal texture, but also not increasing the carrying burden, with uniform weight distribution, avoiding tilting and slipping when carrying, adapting to the carrying needs of modern people. Dimensional tolerance: All dimensional tolerances are ≤±0.1cm, ensuring that the size of each product is uniform. The self-developed version design accurately reproduces the vintage style, adapting to bulk purchase and collection display, and avoiding inconvenience in storage and uncoordinated placement caused by dimensional deviation. Supporting parameters: The collection self-developed version is equipped with self-developed vintage metal tableware (1 spoon + 1 fork), the tableware material is the same as the box body, adopting the same self-developed metal ratio, the size is suitable for lunch box storage, balancing practicality and vintage integrity; All versions are equipped with self-developed vintage linen storage bags, which are convenient for carrying and collection, protect the metal surface, avoid oxidation and collision. The storage bag design integrates vintage elements, keeping consistent with the style of the lunch box.