Modeling and structural design are an important part of commodity packaging. The design of packaging structure is based on the actual conditions of packaging and production, and the design of the external structure and internal accessories of packaging according to scientific principles. When designing, we must ensure that the structure has sufficient strength, hardness and ability to resist other environments. We should consider from two aspects: one is to protect the primary function of the product, and the other is to meet the important characteristics of modern packaging, such as transportation and processing characteristics. Qualified carton products start with correct structural design. Designers should not only really understand the customer's intention, but also be familiar with the post-processing technology. Only in this way can the customer's intention be transformed into qualified products and the post-processing of products be guaranteed to proceed smoothly. Designers should know the nature, shape, size and weight of the contents before the design begins; Arrangement mode, transportation mode and stacking mode of contents; Information such as storage environment, transportation route and time, carton type and manufacturing materials. After determining all kinds of information, it is also necessary to know whether the cartons required to be designed focus on transportation cartons or sales cartons. Sales-oriented cartons belong to the category of commercial packaging, focusing on the appearance and image of cartons, and the requirements of printing technology need to be considered when designing. Transport cartons belong to the category of industrial packaging, so it is necessary to consider the requirements of compression resistance and shock resistance of cartons, and design the position of opening and die cutting without affecting their strength. Because of its repeated use, it is also necessary to consider the efficiency of packing and the production efficiency of the factory. When the required carton type is determined, the design work can be started, and the following problems must be paid attention to when designing. Strength problem: The design of corrugated board is the primary content of strength design. Cardboard can be divided into single corrugated board and multi-layer corrugated board, and there are several corrugated boards A, B and C for each layer to choose from. Please make arrangements according to the understanding before design. When designing the carton type for export, the weather and transportation conditions in transit should be taken into account. As the packaging of bulky goods, corrugated boxes should be designed as simply as possible, easy to handle and avoid die cutting, so as to avoid too many die cutting processes to reduce the overall performance of cartons and make the process too complicated. At the same time, we should also consider the convenience of packing, and some also need to consider factors such as mechanical packing. According to the local transportation and handling situation, humanized design such as handle holes can be added to the larger packing box to facilitate handling. Material selection: the selection of carton material is an important part of strength design, which not only affects the printing effect, but also affects the physical properties of corrugated boxes after molding. For example, there is a close relationship between the moisture content of paper and the strength of carton. Different weather conditions should be taken into account when distributing paper in cartons. When distributing paper for export cartons, the raw paper must have higher physical properties. At the same time, the produced paperboard must also meet the requirements in physical properties such as bursting resistance, edge pressing and adhesion. An important reason why cartons and color boxes are favored is their advantages of environmental protection. The use of consumables such as ink, additives and polishing agents, the recycling performance of paperboard or composite paperboard itself, and waste disposal must meet the requirements of environmental protection. When used as food, medicine or children's toys packaging, whether it meets the requirements of hygiene, health and safety is a very noteworthy issue. Of course, as the packaging of exported goods, we should consider the relevant laws and regulations of the destination country. Size: When designing the size of corrugated boxes, we should not only reasonably set the ratio of length, width and height of corrugated boxes according to the contents, but also consider combining with different container types, so as to make full use of the space of containers, avoid the waste of space during the transportation of products, and be conducive to the transportation safety of products. Printing process: The design work should also consider the differences between different printing processes. The printing methods commonly used in corrugated boxes in China mainly include offset printing, flexography and gravure printing. The change of printing mode directly affects other processes, even the printing materials have to be changed. For example, if you choose to coat white board paper, it is difficult to print with water-based ink flexography. According to the characteristics of different printing methods and other aspects of design, the process scheme can be comprehensively considered. If you use the current popular flexographic printing technology for cartons, you should pay attention to the layout. When designing fine lines, small characters and patterns with dots, flexography should not be arranged on the same page as a large-scale full version. Because of the large printing pressure on the full page, it is easy to make small characters and patterns deform, the printed products are blurred and unclear, and there are quality problems such as broken lines, font strokes falling off and dot loss, which will accelerate the wear or crush the printing plate. If it must be designed on a printing plate, then the exposure time of the full-page field and the fine graphics and texts cannot be the same, and it is necessary to extend the exposure time to improve the hardness and printing resistance of the printing plate at the fine graphics and texts. Carton printing generally has more color plates, and the plates should not be cut too scattered when making up. It is best to make the plates of the same color into a whole. Be careful when pasting the inevitable loose plates and small plates, otherwise the small and fragmentary plates will be damaged and lost in the printing process because they are not firmly pasted in the production process. In addition, when pasting, maintaining and replacing small or fine pattern and text printing plates, do not pull hard to prevent damage and tear. In order to overcome the problems of uneven and rough surface of paperboard, it is required that the printing plate should be wear-resistant, strong in impact resistance, moderate in hardness, good in resilience after being pressed, evenly inked and uniform in thickness. According to the size of patterns, characters and lines and the material situation of corrugated board, the layout design, hardness requirements and manufacturing methods of flexographic plates should be changed accordingly. When the quality of corrugated board is poor and the full-page solid background color is printed, the thicker and softer flexographic plate is selected; When the quality of corrugated board is good, and fine patterns, small characters and screen plates are printed, the flexographic resin plate with high hardness and thin thickness is selected. If the corrugated board has uneven surface, warpage, powder dropping and galling on the printing surface, and sand particles in the paper, it will cause paste, crush, wear or damage the flexographic resin plate and shorten the service life of the printing plate. Therefore, the quality of base paper should be strictly controlled in the production process of corrugated board. The external decoration effect of carton products plays an increasingly important role in product marketing. It can be said that excellent packaging design is an important link to build marketing power and enhance brand image. Decoration design is the content of packaging visual design, which refers to the surface design of packaging, including how to specifically choose colors, graphics, characters, trademarks and barcodes to beautify and promote goods. For the design of sales carton packaging, we should follow the principle of "striking, understanding and liking". Eye-catching: it means that the packaging should combine novel and unique shapes, bright and dazzling colors and beautiful and exquisite patterns, so that consumers will have a strong interest as soon as they see it. The color design of packaging and decoration, attached to graphics, words and texture, not only requires beauty and generosity, but also meets people's perfect requirements, and should be highly coordinated with people's psychological feelings. Color beauty is the most easily felt by people, and it is the first factor that determines sales. Long-term practice has proved that red, blue, white and black are the four major sales colors, which can arouse consumers' goodwill and interest when used as sales colors. Patterns should be combined with colors to set off goods, fully display the characteristics of brand trademarks, and enable consumers to immediately identify products from trademarks and overall packaging patterns. In the packaging and decoration design of cartons, designers should fully consider the abstract expression rules of different colors, so that colors can better reflect the attributes of goods, stimulate consumers' desire to buy, and meet the needs of different consumption levels in the target market. Attention should be paid to the collocation of cold and warm colors, the harmony, contrast and division of colors, and finally make them unified and coordinated into the whole packaging. In a word, pay attention to the feeling of color in the design of carton packaging and decoration, and apply the theory of color psychology reasonably to reflect the characteristics of packaging. Unique modeling is mainly realized by special-shaped structure, which needs to be realized by designing special structural elements such as functional structure (such as handle, hand hole or vent hole, adhesive front piece of automatic folding carton, etc.), characteristic structure (such as corner cutting, hollowing out, legs, etc.) and appearance structure (such as non-cylindrical structure and non-planar structure), so that they can meet the needs of various packaging styles, beautiful modeling, ingenious structure and diverse forms, and attract consumers' attention. Understanding: It means that packaging truly conveys the product image, so that consumers can accurately understand the product through packaging. For carton and carton packaging, the information of the contents can be conveyed by opening a window on the packaging container, drawing product graphics, printing product photos, and making concise text descriptions. Accurately conveying product information also requires that the grade of packaging should adapt to the grade of the product, and it is a failed packaging to cover up or exaggerate the quality and function of the product. Good feeling: It means that the shape, color, pattern and material of the package should arouse people's favorite feelings. Good feeling comes from two aspects, the first is practical, that is, whether the packaging can meet the needs of consumers in all aspects and provide convenience. Good feeling also comes directly from the feeling of packaging shape, color, pattern and material, which is a comprehensive psychological effect and closely related to individuals and their environment. For example, women and men like different colors, and each nation has different favorite colors. Color should be combined with emotion, folk custom and situation in design.