MAST - Modular Asset Staging Tool

MAST is an editor extension for Unity, primarily intended for staging 3D modular assets. It is very useful for making scenes and levels that are based off of a grid. Instead of having to drag a prefab into the inspector, then manually move, rotate and flip it, MAST provides a simple interface that lets you do all the above before ever placing the item in your scene.
MAST includes a fully customizable grid that can be raised or lowered at the click of a button, the ability to customize position offsets, and even a robust randomizer for varying props. Since MAST works with prefabs, there is no limit to what can be placed, including game-ready objects with internal logic components.
Also, MAST can merge static meshes at any time for efficiency at runtime. Also included is a material painting system that brings all your materials into an easy-to-use palette! Everything you do is in the Inspector and can be managed like any other game object.