If you google "paula saddle cake" (since Paula appeared in the file name) you'll discover that this work of art was made by Cake Creations by Paula - Tulsa, OK. However the links to the website of the same name don't work.
Haha, I solved part of your mystery but not what kind of impression or mold you'd use for the beautiful design on the side.
Aren't there impression mats made for gumpaste and fondant, like lace type things? I've seen them on here before, and I think you can buy them at global sugar art. I think a big part of it will be the color you use, too. http://www.globalsugarart.com/cat.php?cid=816&s=30