This is a paid asset, but now you can download Prototype Environment Free.
Detail this asset from Unity Store: Original Link
Prototype Environment v1.1 (Latest version)
This package contains 105 prefabs of the basic shapes and figures with PBR materials.- 36 basic blocks (6 different materials): Wood, Metal, Dark metal, Concrete, Bronze, and Copper.
– 28 Advanced Primitives. Gems, Stars, etc.
– 8 Road. Line and Turn. Asphalt, gravel, dirt, grass.
– 6 Wooden constructions. Floor, Floor with metal, Wall, Block, and Ramp.
– 6 Fences. Each model is different.
– 4 Metal obstacles. Short, long, Column and box.
– 4 Brick constructions. Floor, Wall, Wall with a hole, Derelict Wall and Column.
– 3 Plane with a blueprint.
– 2 Shooting Silhouettes. Light and Dark.
– 2 Basic blueprint block.
– 1 Ground. Dirt.
The textures are made special for Standard Metallic Shader and contain AlbedoTransparency, MetallicSmoothness and Normal maps (2048×2048).