Someone wants me to cover the cake in multi coloured bc before covering in fondant. I figure the best way to do this is the make bc, divide it into different bowls, colour it and then make thin layers one on top of the other before covering.
Have any of you done something like this? and if so, will it work or is there another way?

I have never heard of such a request. If I were to honor it, (which I probably wouldn't), I think I'd load up several bags with the icer tip or my preferred tip, #12, and pipe spirals or lines with each color, then smooth with Viva before covering with fondant. I wouldn't even attempt to ice different colors on top of one another. Not only does it sound like a disaster waiting to happen, I imagine it would look disgusting when cut.

Now I'm worried! I think I'll follow your instructions or I might call her and explain that I was hasty in responding but in retrospect this may not work. Thanks.

Or maybe start with one colour at the bottom, then pipe on a lighter colour above and then an even lighter shade at the top like an ombre effect? Smooth down so it blends and voila, "multicoloured" buttercream

ie below, just smooth it over and put fondant over it. Then when cut, the buttercream will be seen throughout the slice, from dark bottom to light top

Oh wow, that's awesome and perfect, thanks!

Tails, just wanted to let you know that it worked a dream and the girl just loved it. I did 5 different colours graduating from light to dark so that when it was cut you could tell it was like a rainbow, just beautiful & I will definitely be using this method again.
Thank you so much!