Unity continues to improve its engine’s editing features with the acquisition of ProBuilder and Polybrush tools. The creators of these level design suites, which allow creators to quickly and easily sketch out greybox levels and sculpt meshes within the Unity editor, will join the engine developer as part of the deal.
If you're not familiar with ProBuilder, this video is a good showcase of its quick, accessible greyboxing tools:
The tools will also be added to the engine’s development roadmap, eventually being folded into the core editor. In the meantime all Unity subscribers can now download ProBuilder and Polybrush for free to help improve their level design pipeline. ProBuilder is already fully integrate into the Unity 2018.1 beta, which is available right now.
Anyone using an older version of Unity can grab it from the asset store. This version of ProBuilder will not be updated with new features going forward, as development is now focused on the integrated version found in Unity 2018 and beyond. You can find more information about all of these new features, including tutorials and further reading on the official Unity blog.