This fence has been made using a combination of the wall tool and the fence tool.
Start by drawing 1x1 rooms along the length of the plot. If you want them to be right behind the pavement tiles, use move_objects on.
Add a floor tile to the top of each 'room'.
Decorate the outer walls of each 'room' and add a fence by dragging from one end of the plot to the other.
Rotate so you can see behind the fence a little more clearly. Use the terrain tool (smallest setting) to raise the terrain about 4 clicks until you have a peak sticking out of the ground.
Next, add one piece of foundation, dragging from the peak. This will create a piece of foundation which is higher than normal.
You're going to use this piece of foundation to help you level the walls and make them shorter. Open the cheat console again and type boolprop constrainfloorelevation false. Press Enter.
Use the terrain levelling tool to drag out from the foundation to one of the walls.
If you've got this right, you can then drag across to each of the 1x1 rooms to make them shorter.
You should end up with something like this:
So far, so good.
Add some gates and some other adornments and you have made yourself a custom fence.
Don't forget to turn off all the cheats and delete your little piece of foundation that you used for levelling.
You can play around with the idea a little, creating walls of different heights and adding statues and lighting etc. Have fun!