# Comparison of CAD Software for Designing Cellular Structures for Additive Manufacturing
## 1 Introduction  
Additive manufacturing (AM) technologies are leading many different industries to rethink traditional production possibilities and enable even small batches to be manufactured in a cost- and material-efficient manner. Compared with traditional manufacturing processes such as machining, the use of fewer primary materials, thereby being more resource-efficient, as well as the elimination of chips and harmful process additives, such as cutting fluids--a major source of hazardous production waste threatening terrestrial, atmospheric, and aquatic systems--makes AM a state-of-the-art manufacturing solution compatible with future goals such as sustainability and increased environmental protection [1]. The evolution of various AM processes has both disruptive and industry-evolutionary implications [2; 3; 4]. With the help of AM, fundamental changes in society in the areas of consumer behavior, industrial manufacturing, and education can be triggered. AM has implications for society both in terms of industry and in terms of the manufacturing of components by so-called \"makers\" in their own home spaces [3]. In the industry sector, on the one hand, employees at all levels of the supply chain must be retrained. On the other hand, because of the high level of automation and the continuous digital process chain, many manual, labor-intensive jobs will be lost. This effect can be compensatedfor by highly qualified training, which is required for new jobs in the AM industry [5]. However, because of patent restrictions on many AM processes, the actual impact on the manufacturing industry as well as on society as a whole cannot (yet) be estimated at this point in time [2]. The rapid development of new, innovative, and alternative manufacturing methods, which have made great strides in recent years, particularly in the area of additive manufacturing, has likewise opened up new possibilities for component design and part construction [6; 7]. The continuously growing variety of materials [8; 9; 10] and the ability to rapidly manufacture geometries and designs that cannot be produced conventionally make it possible to integrate new design structures into part volumes to be manufactured. Similar to truss constructions in the building industry, which use wood or steel, in order to achieve the desired product properties in additive manufacturing, lattice and support structures are used [11; 12]. Lattice structures are an important tool for providing larger, normally massive volumes with a certain porosity in order to save weight while maintaining the same load-bearing capacity [13; 14]. These make it possible to manufacture free-hanging, thin, or heavily protruding features with the least possible additional material input. These structures, usually built from strut-based lattices, are added to the given part manually by the user or automatically by the corresponding software program during part preparation. This support method, which allows for the most stable and warp-free manufacturing possible, is often used in Powder Bed Fusion (PBF) of metals (e.g., Selective Laser Melting--SLM, Direct Laser Metal Sintering--DLMS, Electron Beam Melting--EBM, etc.) [15; 16; 17; 18; 19] and Vat Photopolymerisation (VPP, e.g., Stereolithography--SLA, Digital Light Processing--DLP, etc.). Similar is the case of the filling of bodies with larger volumes, or the connection of two separate walls. It is possible to determine the degree of filling of the volume in order to save manufacturing time, material, and weight. Generated lattice structures can either be uniform, with identical cubic geometries, regardless of the imported body's shape (constant, non-conformal, and strut-based) [20; 21], or gradient cubic-based structures that adjust the distance between vertices or the thickness of connecting struts to more closely conform to the original model's shape, thereby allowing for local density variations (conformal or gradient lattice structures) [22; 23; 24; 25; 26; 27].