Know Your Software
The first thing to understand about 3D printing software is that, most likely, you will need more than one application to bring your object to life. We say "most likely" because some apps do roll all of the necessary features into one, but they are usually expensive, or not as good as a standalone alternative. In any case, the two types of software you are looking for are 3D modelling applications and slicing applications.
As the name suggests, 3D modelling applications allow you to create a model digitally. Free of the constraints of the physical world, you can make anything your imagination can conjure up without spending exorbitant amounts of money on modelling clay or some other physical medium.
Slicing software, on the other hand, takes that 3D model and cuts it up into several layers. It does this because the 3D printing process isa form of "additive manufacturing", which builds the item up layer-by-layer. Your slicing application can break your model down into these layers so that they can be handed off to the 3D printer.
What is the best slicing software?
Now that we know what we're looking for let's get into some examples of slicing applications. It's worth noting that most 3D printers will come with their own slicing software. If yours doesn't, or you want to try something different, here are a few excellent alternatives.
Slic3r is an open-source slicing tool that is continually being improved by the passionate community that has grown around it. It works with a wide variety of3D printers from several manufacturers. The good thing about open-source software with an active community is that it is very easy to find help if you get stuck.
Cura is also free and open-source, although this one comes from the minds at Ultimaker-a 3D printer manufacturer. It has a deceptively simple user interface but packs a lot of features. It is an excellent tool for beginners thanks to that simple UI but has plenty of customization behind the scenes for more experienced users.
Simplify3D is a commercial tool and the preferred slicing application for many professionals. As is usually the case with commercial software, Simplify3D offers more features and overall improved experience over its free alternatives.
What is the best 3D modeling software?
3D modelling is not something most of us can just pick up and be good at. While there are plenty of applications out there, you should be aware that it will take a bit of time, patience, and practice to get good at 3D modelling-especially if you've never done anything like this before. Now, onto the 3D modelling applications!
SketchUp is a very user-friendly 3D modeling application that will make a great starting point for those new to 3D design. That being said, it is still a compelling application that experts will be able to get a lot out of. SketchUp is aimed more at design, so it is not ideal if you are making artistic pieces. If you need precise details, however, such as prototype components, this is the app for you.
Brought to you by 3D design industry veterans, Autodesk, TinkerCAD is a browser-based 3D modelling tool that is specifically designed for beginners. Unlike SketchUp, TinkerCAD doesn't pack much of a punch, but it is very intuitive and easy to get to grips with. If you're just starting out, this is a great application, although you may find you'll need something more powerful as you improve.
OpenSCAD is a different twist on 3D modelling. With this application, you write code in scripts. These scripts will then generate the 3D model, which can then be used for 3D printing. OpenSCAD is a particular niche within the 3D printing community, but if you like to code, this could be a handy application for you.
As the name suggests, FreeCAD is... well, free. It is an open-source tool that is community developed, meaning there is usually plenty of help on hand if you ever need it. Like most applications with "CAD" in the name (computer-aided design), FreeCAD is better suited to prototyping and printing individual components of a larger assembly than it is at making intricate artistic models. It even comes with tools for engineering simulations, so you can check that your assembly functions the way you want it to before printing.
Yet another open-source application, Blender is a very popular 3D modelling application that is under constant development and has a strong community around it. When it comes to free 3D modeling software, you won't find better than Blender.
This is by no means a definitive list. There are many applications that we have left off, some free, some commercial. We had to stop somewhere, but we thought a few other names deserved at least a mention. So, if none of the above catch your eye, perhaps give these a look;