Modular Sand Dunes

As we already know, I'm working on a game table. The table will have a tile-type of "ground" and two sand dunes to go with it. Originally I was going to have the sand dunes glued to the table. Now I've decided that the sand dunes will be removable. Then I can position them however I wish without having to rotate the table all the time. I don't know why I didn't think of this before.