This is a paid asset, but now you can download MBS – Modular Building System for FREE, but please remember this package is provided only for learning purposes or to be able to test before buying the product, NOT FOR COMMERCIAL PURPOSES.
Detail this asset from Unity Store: Original Link
MBS – Modular Building System v0.2
Tool for fast and easy prefabs placement in the scene. You can use custom modular parts with any geometries, textures, materials, scripts, and components.
Warning! MBS is in early access and in active development. You can use it as you need, but it is not a ready solution for production yet.
MBS v0.2 contains 3 main tools:
Wall Builder Tool
Floor Builder Tool
Decorator Tool
With Wall and Floor Builder tools, you can easily and quickly create a building structure or mockup your level. Using the Decorator tool, you can quickly fill your building or your level with decorative and interactive parts.
You can use custom prefabs with MBS. With Decorator Tool you can use almost any prefab, but for Wall and Floor Builder tools you may need to make minor adjustments such as centering pivot point and few others. See more on the MBS Assets Creation Guide page.
You can create your own modular pack for MBS by following just a few rules. Such packs can be shared or sold.
The ultimate goal of MBS is to create a fulfilled system for creating buildings and other structures out of modular prefabs (walls, floors, roofs, stairs), and quick and easy placement of decorative and interactive prefabs in scenes.
See supported Unity versions in Technical Details.
Features:
Wall Builder Tool
Floor Builder Tool
Decorator Tool
Floor Mesh Generator