So I got an order for a small tiered cake for 40 people, a 4,6, and 8 inch is what I figure Minnie Mouse they provided a picture they copied from Pinterest, the dilema I have is that the cake is decorated 100% in fondant and they want Buttercream!! They still want smooth lines and the polka dots and Minnie face which would be easy to make with fondant or at least easier and they want Buttercream. Anyone have any suggestions? Anyone had to do this? Any help is appreciated. Thanks 

I have made many many cakes show with/fondant Using buttercream:)   When you’re not used to using buttercream it might seem hard but it really isn’t:)   If you have a lot of problems you can try thickening the buttercream just for the face 

I am not worth a hoot at buttercream and frankly, I would tell them Minnie would be fondant or I would not do it.  I could certainly do a Minnie Mouse, but I cannot start to imagine what a mess it would be!

If you don't feel comfortable doing it all in buttercream I would tell them that the accent pieces (Minnie Mouses face and polka dots) will need to be done in fondant.  I get that people don't like fondant but I think having a cake that is primarily buttercream but the accents are fondant is a pretty good compromise.  The reason they probably like the picture they pulled from pinterest is because of how clean it looks due to the fondant, so just explain that doing that all in buttercream will not result in the same effect, that you can certainly get a smooth covering on the cake with buttercream but that the accent pieces would be better in fondant.

The only other thing you could do is make buttercream transfers for the polka dots and even Minnie's face, but that may take a few practice attempts if buttercream isn't your thing (I know I would probably end up throwing the piping bag across the room a few times LOL!)