I am making a cameo cake it calls for a crusting buttercream. However I do like to use all shortening I like to use all butter. I need the icing to set up firm so I can smooth out the icing using either a fondant smoother or viva paper towel method without smearing the camoflouge colors together. I could I add merique powder to my all butter buttercream icing would that set firm ? Any suggestions welcome..

Thanks

Well what makes b'cream crust is the amount of fat (no matter what kind) vs sugar.  The more fat the *less* it will crust. Butter contains more moisture (water) than most shortenings.  Try using 1/2 butter and 1/2 shortening and about 1/4 or 1/2 less than usual.    Also, check out my recipe "2 of everything" posted in the recipe section.  I tried to find the link but got a weird message :(   If you are lucky enough to find the recipe be sure to read through ALL the comments as there is much additional information included there.    Meringue powder really doesn't help much - y ou are much better decreasing the fat amount used.