Help with icing a no. 6 birthday cake!

[whateverfloatsyourboat]

Can I ice a number cake in a careless, glace-icing-sprinkled-with-smarties sort of way, or will that look rubbish?

I iced DS's number 6 cake in butter icing, cut some 6's out of pre-made roll out icing then stuck a load of his lego mini-figures in it.

I find butter icing easier than glace which I always make too runny.