Idea of Do Not Stack Icon
This icon has two three dimensional boxes that are sitting on top of each other. A long slanted, horizontal line is going through the middle of both of the boxes.
This Do Not Stack icon is made in Material Design style
developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 6,100 icons, all in the same style and quality.