Flower Decorations

[Alycat6390]

Hello all!
I am doing a wedding cake that will have a bunch of small violet shaped flowers on it in different colors. I wanted to know if you all think it would be easier to do them in buttercream and freeze them to put on the cake easier or royal icing and do them ahead of time. I have attached a photo for reference. The cake will have round tiers instead of square like the picture. TIA!

 

[retired baker]

bagged with royal icing all day long for those.
buttercream is prone to pick flavors and condensation.