I have made several fondant covered wedding cakes, but this will be my first buttercream. She would like satin ribbon on it, again, something I've not tried. She wants polka dots which should work fine and talked about quilting. The only way I can think to do that is score the frosting after it's dried and put RI lines on. Sounds like something that could be crooked pretty easy.
there are impression mats that you can buy to impres the diamond look into the buttercream. is that what you mean?
Well, since Crisco is made now with no trans-fat, working with buttercream is a little troublesome as more often than not it does not crust properly to give it a smooth finish. I suggest that you mix Crisco with whole milk to add the missing fat needed for it to crust. Don't forget to add Wilton meringue powder to stiff it. Once the icing is stiff you can create the quilting using a flexible ruler. When using ribbon attached to buttercream it gets stained with the fat; there is a waxing method to fix it but I am not sure how it's done. Good luck.
Use Indydebi's buttercream recipe. It uses regular old Crisco, and it smooths easily and crusts beautifully-tastes great, too. I use it for everything, and I have quilted cakes covered in it using an impression mat. Here's a link to the recipe:
u-tube has good video's on bc watch enda's and personally i would do the poka dots in bc also, ri is so hard it can break a tooth.
I'm not sure if this recipe is as good as indydebi's - but designmeacake.com has a great crusting cream cheese buttercream recipe. I've used this recipe a few times and everyone loved it.
Also, Earlene's has impression mats for only $6. They ship very quickly and shipping costs are minimal.