CNC Design – An Introduction to Designing & Making Things


Woodworking and carpentry have been around since time immemorial, and today there are still many of us who prefer personally made home additions. Store-bought furniture and flatpack décor just don’t give the same feeling of personal pride that comes with designing and making things yourself.

As technology grows, so does our potential to make bigger and more complicated things in easier ways, and this is where CNC machining comes in.

This guide was mostly written for hobbyists looking to make fun CNC router projects, but also applied for commercial uses.

CNC Design

Subtractive Manufacturing: What is CNC?

CNC designs primarily involve what’s called subtractive manufacturing. Those of you familiar with 3D printing will see this as the opposite of ‘additive manufacturing.’

CNC machines are precise cutting tools for shaping solid materials into whichever shapes are necessary to make signs, furniture, ornaments, and even jewelry.

A piece of wooden furniture creating using CNC

Subtractive manufacturing simply means that planks and blocks of materials like wood or metal are cut to create a desired form or shape. This is no different from sculptors removing parts of wood or stone to make statues.

While it may seem like CNC designs don’t quite match the ‘making it by hand’ mantra, the pride of making things yourself with CNC machining is no less diminished by automation. Designing things to make with CNC technology still requires the creativity and forethought that goes into any DIY work.

What can you design and make with a CNC router?

CNC wood designs are normally what comes to mind when people think of CNC machining. However, there are many more materials that are compatible with CNC designs to make a host of different things.

As well as wood, most metals such as brass, copper, and steel can be cut, milled, turned, machined, and drilled with CNC machining. With this technology, you can make a wide variety of homemade projects like chairs, shelving, jigsaw puzzles, and even guitars!

Milling a piece of metal

Here we’re going to look at the best ways to create CNC designs to bring your ideas to life.

How to Get Started with CNC Design

Get Your CAD

CAD software is how CNC designs are created virtually before being sent to the machine to tell it what shapes are to be cut or engraved.

The majority of CNC manufacturing involves CAM software, which is how the process of manufacturing is automated after the CNC design has been uploaded to the machine.


For newcomers to CNC and designing, we recommend that you trial and/or buy your CAD software before getting your CNC machine. Doing this will give you a chance to get used to the software and how it works, letting you ease yourself into CNC design.

By getting used to the software first, you’ll avoid being overwhelmed by having to get used to both new hardware and new software at the same time.

Whichever CAD software you choose will depend on your previous experience. Beginners to the design process or CAD software, in general, will benefit from software like GRBL or Easel, while those of you already used to CAD software will need to shop around to find more complex programs.

If you’re still unsure, you can look at our article on the best CNC software for all skill levels.

Know What File Formats You Need

Whichever CAD software you choose, you’ll need to get used to converting and exporting various file types to suit your machine.

It’s never fun to find a design you love only to learn that its format isn’t compatible with your software. Because of this, it’s important to note which file types your machine supports.

The most commonly supported file types for CNC design are STEP and IGES, but STL files, DXF, and DWG are also used. Increasingly, software and machines can automatically convert your CNC files to STEP before manufacturing.

If you’re working with 3D models when designing with CNC, you’ll need to become familiar with other file types, like SLDPRT and 3DM. This may sound a little overwhelming, but if you use the software that came with your CNC machine, you should be able to get a good handle on which files to use, and how to convert them manually if needs be.

CNC design toolpaths in software

2D and 3D designs will use different file formats, but .DXF files are most commonly used when moving CNC designs between different kinds of CAD software, as they are almost universally compatible.

More complicated versions of these files are called ‘raster’ files, which are essentially raw JPG or PNG images that need to go through a process called vectorization to be converted to a usable CNC design file. While this can be done manually, there are software online like Inkscape that will turn 2D images into usable vectored files for CNC use.

The files that will eventually guide the automated manufacturing process are brought in by g-codes. G-codes are effectively the language your CNC router runs on, telling the lathes where to move and how by converting the shapes we see in our design software to a numerical code that will be read and interpreted by your machine.

For more info, read our article on g-code and m-code.

Settle on Your Idea

Of course, before beginning with your CNC designs, you’ll need to know what it is you want to make. If you’re a professional user who is using CNC machining to create or prototype pieces, you probably already have a good idea of what you’re going to make.

But if you’re lost for ideas, you can check out some of our articles on the coolest and most useful CNC projects or, if you’re looking to make some money with your designs, you can check out great CNC projects that sell.

If you’re a hobbyist, you probably bought your CNC machine with a few project ideas already in mind. But it’s also important to know what kind of material you need and ensure you have enough.

Some projects, like instruments, need exactly measured shapes and pieces to make sure you get the sound you want when in use, not to mention specifically chosen materials. For chairs and tables, you’ll want to make sure you have a sturdy enough material to support enough weight.

Not only does double-checking your materials make the end results safer to use, it also ensures you don’t waste any money on materials you didn’t need or can’t use.

Once you have your idea and have decided on the necessary materials, you can begin designing.

Decide Your Toolpaths

CNC cutting design isn’t quite as simple as drawing what you want and sending it to the machine to do the rest. Because CNC designs involve cutting and engraving, the depth, width, and other size dimensions are important.

These dimensions need to be precise to ensure the end result is as close to perfect as can be. This will not only save time and material but ensure more practical projects, like guitars and furniture, are dependable and fully usable.

CNC Toolpaths

While errors in these dimensions are easier and cheaper to deal with when making CNC wood designs, metal materials are both harder and more expensive to replace. And so, these dimensions are important to get right.

These directions are called toolpaths, and they are essentially exact instructions that tell your CNC router how to move when cutting. By programing these toolpaths, you’ll be telling your router where to cut and how.

Once your toolpaths have been selected, you’ll then need to decide which tool you’re going to use, be it cutting, drilling, or engraving. Then you can import these instructions to the machine and let it get to work.

Hints and Tips

When using any tool or machine, knowing as much as you can about efficiency and, most importantly, safety. CNC machines, regardless of their type and capabilities, are no different, and it’s a good idea to get a decent understanding of your toolset.

Know The Limits of your Machine

Every machine has its own limitations regarding what it can do. Not all engravers can cut metal, and not all CNC routers can be used for all purposes.

Familiarizing yourself with the limits of your router is important in CNC design. By overestimating what it can do, you can end up wasting materials or even risk damaging your machine.

Milling a metal block

The limitations of your machine will also deteriorate without proper care. Rusty blades are dangerous, dull ones will strain both the machine and the material.

Understand the Importance of Dimensions

As we’ve mentioned before, getting the dimensions of your design as accurate as possible is imperative to the quality and usability of your projects.

These dimensions don’t just involve width and depth, but also the roundness of edges, and the angles at which corners and perpendicular parts are cut.

A CNC machine cutting dimensions specified from the original design file

For decorative pieces, the acceptable margin of error will depend on how much of a perfectionist you are, but workable CNC designs like musical instruments will need a level of precision that should be double- or triple-checked in the design phase.

Know What Tools You’ll Need

Particular dimensions will require specialized tools like specifically sized drills and lathes. There’s nothing worse than working hard to make the perfect CNC design and then finding out you don’t have the hardware to bring it to life.

Like any DIY project; ensuring you have all the tools you need, making sure they’re fit for use, and organizing them will streamline the process and rid you of any potential unfortunate tool-related surprises.


Before you get to work on anything, make sure you do your research on just about every step.

It’s important to know which machine suits your needs so you can be sure you’re getting exactly what you want before paying for it. You do not want to realize far too late that a particular project requires a machine capable of things that yours simply isn’t.

It’s always a good idea to select and get to know a particular CAD software before putting it to active use. While there are many examples of free CAD software out there, many of the paid ones do offer free trials, so there’s no reason to not shop around and experiment to find out which one is right for you.

Some of the different types of CNC machines

The CAD software you’ll select will depend on your experience and skill level. Beginners will want a simple learning curve, while those who have used design software before will likely not be interested in the more beginner-focused programs.

Finally, you need to research what kind of materials you’ll need for each project. This doesn’t just refer to the type of wood, plastic, or metal, but also the lengths and depths of each type. Making sure you have all the materials you need and of the right type will reduce the risk of complications mid-cut.

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