Texture/material customization

For some or all objects, the ability to customize some aspects of appearance would greatly add to the ability to customize environments.
Example:
Apply custom texture to floors and adjust reflectiveness.
Select object with a metal texture and change from steel/iron to brass/copper/gold.
Select something made of glass and make it look dirty/clean by adjusting transparencies

Even if only things like walls or floors were affected, this would still be a solid addition while we all wait and hope for workshop and custom model support.