The Role of CAD Modeling in 3D Printing
Sep 26, 2026
The first step in manufacturing is to think about what your final product may look like. Visualisation is the key for every designer, engineer or manufacturer. A visual representation of our imagination can help in understanding the shortcomings of a design.
As 3D printing enthusiasts, you probably understand the importance of creating a 3D model. The translation of an idea into a pictorial 3D figure sets the tone for the entire production process. The one piece of software that 3D printing cannot do without is CAD.
In this article we will look into:
- What is CAD?
- A brief history of CAD
- Types of CAD modeling
- CAD file formats for 3D printing
- What does one need to build their own CAD software?
- India's potential in the CAD world
What is CAD?
CAD stands for computer-aided design. It is used to create, analyse and modify designs for pictorial representation. It is a common tool for designers across architecture, construction, automobile and aerospace.
The software was initially developed in a computer language called Fortran. However, with the introduction of object-oriented programming there was a significant shift, which led to CAD software based on a parametric feature modeller. It started to use the C language and build APIs.
CAD systems architecture has three main components: the GUI, the operating system and the database. The GUI in CAD is built using NURBS geometry and boundary representation (B-rep) with the help of a geometric modeling kernel. CAD now supports Windows, Linux and macOS, and is capable of running with minimal hardware requirements, which makes it accessible and easy to use.
How CAD is used in 3D printing
3D printers run on a set of instructions, and those are captured through 3D modeling in CAD software. A file generated from CAD is later used by the printer to produce the model, and it also helps determine material requirements and the structure of the overall design.
CAD software typically generates STL files. STL stands for STereoLithography, sometimes also called Standard Triangle Language or Standard Tessellation Language, and it contains the structural details a computer can read. If you want to know what happens to STL files next, we have an article on slicing software.
CAD is the root of all manufacturing and production, including the composite parts we design and build. Technological advances have made it a key component that is not only advanced but easy to use. Let us look at the journey of CAD to understand how we got here.
A brief history of CAD
It might not be easy for today's generation of engineers, designers or architects to imagine a world without computer-aided design. Before CAD disrupted the world of design, engineers made their models on sheets of paper with large drawing boards, using simple tools (varied grade pencils, set squares, T-squares) to get the most accurate representation.
The early inception of modeling software came about through the need for visualisation. At the beginning, CAD systems existed simply to replace 2D sketch boards and store the digitised drawing of a model. As engineers learned more about computers, they were able to change and modify designs with minimal effort.
In 1957, Pronto was the first commercial numerical control programming system, introduced by the father of CAD, Dr Patrick Hanratty. This led to subsequent adoption by engineering companies, and established firms including Ford, Siemens and Lockheed Martin began using 3D CAD software for their manufacturing. Eventually they upgraded it with in-house tools suited to their own requirements.
Types of CAD modeling
Solid modeling
Parametric modeling: 2D sketches are used to create the model. It has a history tree that can be modified, inscribing features and functional relationships with other sketches. The major advantage is that changing a single parameter automatically adjusts the rest. The framework behind such models consists of mathematical equations, and it is commonly used in designing buildings or structures in architecture.
Direct modeling: Similar to parametric modeling, but without a history tree. This suits one-off designs with very little structural change, and is commonly used for rapid prototyping and short production cycles.
Surface modeling
This type of modeling depends on the surface to form the geometry of an object, allowing you to view it from a given angle. It divides into two categories: parametric and freeform.
Code-driven modeling
This is still at the research stage. Academia is trying to optimise CAD modeling using techniques that automate the framework of the software, deriving a design from a set of conditions provided by the designer. It suits 3D printing well, and can help build 3D structures manufacturable to high accuracy.
CAD file formats for 3D printing
CAD modeling is common across many sectors, but for 3D printing it is the backbone of the technology. Understanding CAD from a printing perspective matters for additive manufacturers. The three most common file types are IGES, STL and STEP.
IGES/IGS (Initial Graphics Exchange Specification)
One of the oldest CAD file formats available. It was adopted by the American National Standards Institute from the US Air Force, which used CAD geometry between 1976 and 1984. It is often unsupported by newer CAD versions.
STL (Stereolithography or Standard Tessellation Language)
This file type was made exclusively for 3D printing by 3D Systems, which is why STL is the better option compared with IGES. STL files divide into ASCII (large) and binary (compressed), and binary is recommended for its smaller size. The biggest disadvantage is that STL does not cater to holes, gaps or watertightness when manufacturing certain products.
STEP (Standard for the Exchange of Product model data)
This format was created for the aerospace manufacturing industry, and the latest version is now being adopted in automotive. It can save layers with colour, and can export itself into an STL file, which helps in understanding solid bodies better.
STEP vs STL: which should you use?
The short answer: STEP for design and exchange, STL for printing.
| STL | STEP | |
|---|---|---|
| Built for | 3D printing, by 3D Systems | Aerospace manufacturing, now adopted in automotive |
| Stores geometry as | A tessellated mesh of triangles | Solid body data |
| Colour and layers | No | Yes |
| Handles holes and watertightness | Poorly (its main weakness) | Better, since it describes solids |
| Converts to the other | No | Yes, exports to STL |
| File sizes | ASCII (large) or binary (compressed, recommended) | Generally larger, but more information |
So STEP has a slight edge over STL for carrying design intent, which is why it is preferred for exchanging models between teams and suppliers. STL remains what the printer ultimately needs, and STEP files can be exported to it.
Popular CAD software in the market
Autodesk
Autodesk is an American company offering multiple CAD solutions, used across manufacturing, automobile, robotics and medical industries.
- AutoCAD 360 (free): mobile and web-based application
- Fusion 360 (paid): cloud-based, popular among mechanical engineers and designers. A good mix of engineering, design and manufacturing.
- Tinkercad (free): popular for 3D printing. Hobbyists, educators and designers use it to make 3D models. Simple and easy, so well suited to beginners.
Dassault Systèmes
Dassault Systèmes is a European company with a wide range of 3D software, covering design, CAD, simulation and process management. Their products are common across defence, automobile and aerospace.
- CATIA (paid): one of the most popular CAD packages in the automobile industry. Companies including Tesla, BMW, Porsche and Ford are among its users.
- SolidWorks (paid): built on NURBS, enabling detailed and intricate models. A go-to option for parametric modeling-based design.
The CAD market is wide and versatile, and these companies have dominated it for decades. As more manufacturing startups emerge, the need for CAD will only increase, which raises an interesting question. What if you made your own software, custom-built for your own services?
What does one need to build their own CAD software?
Many manufacturing companies have built their own software to support production. In-house tools can solve design problems specific to the company, and they can be cost-efficient or even sold as a product.
We took a version of that route at Fabheads, though not with CAD. We built C6, a browser-based slicer with 3D object preview and full control over printer settings, because continuous fiber printing needs slicing parameters that general-purpose software does not offer. The reasoning is the same as for in-house CAD: when your process is unusual, off-the-shelf tools stop fitting it.
If you are considering building CAD from scratch, here are the basic elements to plan for:
- Geometric kernel: the backbone of the entire system, creating the foundation for topology mapping. It is the most time-intensive and research-oriented part of the job. If time matters, third-party kernels such as Parasolid, Open CASCADE and ACIS exist.
- Topology: the mapping of elements like bodies, faces and edges. Management of features is structured through this component.
- Features: design requirements vary by industry. Automotive, for example, needs both surface and solid modeling features.
- UI/UX: rendering of models, pipelines, viewers, textures, outlines and dialogues.
India's potential in the CAD world
Onshape is a CAD system built on a software-as-a-service model, and it has depended heavily on Indian engineers to build, sustain and develop it.
“We came specifically to Pune because there is a lot of CAD and geometric modeling experience here. This will primarily be a development facility, and we may add some support functions later.”
- John McEleney, then CEO of Onshape
There is a substantial talent pool in India with deep CAD expertise, which is why companies from the West have been turning this way.
Conclusion
Almost 60 years after its inception, CAD has evolved into a substantial industry in its own right, a multi-billion-dollar market annually, and the core of many industries including 3D printing. It is next to impossible to imagine what a 3D printing pipeline would look like without it.
Our aim through this article was to understand the role that CAD software plays. We looked at different models and structures that can be built using 3D modeling, and touched on the existing packages in the market. That led us to the components you would need to build a CAD system of your own.
One of the biggest takeaways is India's future in CAD-based projects. Growth in additive manufacturing and composite manufacturing shows a real need to invest in R&D for complex technologies like CAD, benefiting every industry that uses it, from mobility to robotics, and encouraging more startups to build here.
Have a design ready and need it made in composite? Talk to our team.
Frequently Asked Questions
What does CAD stand for in 3D printing?
CAD stands for computer-aided design. It is the software used to create the 3D model that a printer works from: the model is exported to a format like STL, then sliced into layers and converted to G-code for the printer.
What is the difference between STEP and STL?
STL stores geometry as a mesh of triangles and was built specifically for 3D printing, but it cannot carry colour or layers and handles holes and watertightness poorly. STEP stores solid body data, keeps colour and layers, and exports to STL; so STEP is better for design and exchange, while STL is what the printer needs.
Which file format should I use for 3D printing?
STL is the standard input for most printers and slicers. Use binary STL rather than ASCII for the smaller file size. Keep your source model in STEP or a native CAD format, since STL loses design information that cannot be recovered.
What are the main types of CAD modeling?
Solid modeling, which splits into parametric (with an editable history tree) and direct (without one); surface modeling, which builds geometry from surfaces and can be parametric or freeform; and code-driven modeling, which is still largely at the research stage.