In this tutorial you will learn to use the gradient, rectangle, pathfinder and line tool to create a simple envelope. With change in the direction of the arrow, you will have multiple defined icons. Using Pen tool and enable the Point option in the view window. After that remove the middle anchor point and fine-tune its angle. Then choose the nodes of the copy. Adjust the nodes by bringing them a bit up and joining the rectangle’s corners and choose both the shapes and expand it with pathfinder palette. Finally you have a nice an envelope icon in illustrator.