If you are just starting out with 3D printing, you first need a simple way to design your own models. A good choice for beginners is the free web app Tinkercad.
Tinkercad runs directly in the browser, no installation is necessary. It is operated intuitively via drag-and-drop. Complex models can be created by combining simple basic geometric shapes such as cuboids, spheres or cylinders.
Importing SVG and 3D files is also possible. Tinkercad supports the common 3D printing formats STL and OBJ for exporting models. Convenient: Models can be viewed virtually directly in Tinkercad and checked for dimensional errors. Tinkercad also has an iPad-App.
Tinkercad was developed in 2011 by ex-Google developer Kai Backman. In 2013, Autodesk took over the software. Tinkercad is ideal for beginners due to its simple operation. However, advanced users might reach its limits.
As free 3D modeling software that can be used directly in the browser, Tinkercad is ideal for newcomers. However, complex constructions can only be modeled to a limited extent.
FreeCAD as an alternative for advanced users
If the possibilities of Tinkercad are no longer sufficient, FreeCAD is a powerful alternative for ambitious 3D printing users. The open-source software offers extensive parametric modeling tools that approach established CAD programs such as CATIA or SolidWorks in their functionality. Complex and precise designs are possible in FreeCAD.
Moreover, the functionality can be adapted by own extensions via a programming interface. FreeCAD supports all common 3D print file formats. The program is available free of charge for Windows, Mac and Linux. With its comprehensive functionality, FreeCAD is an interesting option for makers who are reaching the limits of simple modeling software and need more control over their designs.
Other alternatives to Tinkercad
For educational institutions (teachers and students), Fusion 360 is also available as a free alternative. This is a more professional 3D modeling software from Autodesk. Tinkercad designs can be imported without any problems.
Another program is SelfCAD. The software is available for the web as well as the desktop (Windows or Mac). The basic version is free, but limited. The Pro version costs $140 a year or $15 a month. There is a discount for educational institutions.