I would suggest either using a real doily or a mold, but I am not sure you can get a mold... Use a little cornstarch on the doily, and roll out your fondant onto it. You will need to strengthen the fondant with CMC / Gum tex. Peel off the doily carefully, cut off the piece you don't want to make a straight bottom, and set to dry. Use cake dummies to dry them out on, so that you get the correct curvature. You need them to dry, or the tops of the doilies will flop over as you place them on the cake. This can take a good few days. Attach with royal icing or mashed down fondant/water.
Here is a pic of one I did that is similar, but these medallions were done with a mold from Elegant Lace Molds. Such a great mold!
Hope this helps

