Overlapping objects is an even stronger method of adding depth and scale to objects. Our brains will always insist that an object that is obscuring the view of another object is closer to us. This method is so powerful it will even override contradicting size and scale information. Look how just changing the overlapping of the tower changes this picture. Corel Draw lets you work with different layers of objects. You may have many layers in a drawing, but only one can be active at a time. Objects that are added to a drawing are placed on the active layer. Corel automatically creates a default Layer 1, which all of your objects will be drawn on, unless you create a new layer. As you create objects, Corel places them in a stacking order, from front to back. By arranging objects on top of each other, or even on different layers, you can create the illusion of depth. Weld, Trim, and Intersection : these commands let you use the shape and position of multiple objects to create an entirely new shape. Welding several overlapping objects erases all of the internal lines and leaves only the outline of the combined objects. Weld is useful for drawing street maps, and for creating complex objects from a series of shapes. The Trim command allows you to use one object to cut overlapping areas out of a selected object. It works like a cookie cutter. The object you trim, called the ‘target object,’ keeps its fill and outline attributes. Trimming is a good way to create irregularly shaped objects very quickly. You can also use the Trim command to divide a single object into two. Using the Intersect command creates a new object out of the area where two or more objects overlap. The new object’s fill and outline attributes depend on the object you define as the ‘target object’. The trim tool works well for creating objects that look like they are being sliced. Source.