This is called skinning. The sweep path does not need to be straight, nor does it need to be the same on all sides. A sweep path with variable sides is called a scaling envelope, and can be used to lathe an object to create something like a vase. A non-straight sweep path can be used to create something like a curved pipe. Spirals can be made using special commands.
Designer supports as many cross sections as are desired.
A tutorial in the user's guide shows how to create a realistically-shaped dinner fork using only one object, a great example of using the different features of Designer's modeler. Features, options, shortcuts, grids, and an intuitive interface make modeling in Designer about as easy as it gets. But for those who wish to avoid it altogether, Modeling WIzards provide a means of creating several predetermined types of objects by simply choosing from sets of options. Wizards can help you create these and other shapes with no modeling. Designer has an extensible architecture, and the Wizards facility may be supplemented by third party developers to increase the number of useful objects that can be created in this fashion.