I do like the effect of this mold. However, if it were possible to flip it over and get a good "underside" coating, that would be helpful. Using it by itself, crates a textured wave. To put a layer on top, in order to flatten it out, you would need to put it in a second coaster mold. Putting it flip side into this mold, will only create more issues. You definitely need a plain round coaster mold, to make these work. Without the second step, they are just too thin and uneven.
But they are GORGEOUS, don't get me wrong. Just not very user friendly.