Using symbols for plans and elevations. One of the earlier posts noted that a symbol instance is consistent throughout the file, so that if you update the symbol definition every instance of that symbol will update. One of the cool tricks is to use your symbol to create both a 2-D and 3-D versions of the symbols that you want. A door might be an example. You could create a symbol that had both the 2D and 3D part of the door. That way if you update any part of the door both your plan view of your symbol and your elevation view of your symbol ( in a separate design layer) would both update.