Im unsure how to do this. Is the string work Buttercream? I can’t see that sticking to the cake well once crusted. Any suggestions?

Looks like it is piped with either a Wilton 4 or 5 tip.  You could use an extruder, but piping would be easier, at least to me.

Practice.  That looks like a fine line between "ooh pretty!" and "huh?"  Maybe royal icing?

Thank you. I need to brush up on my piping skills. I have a really hard time on the sides of a cake. 

It almost looks like it was piped on a fondant covered cake so there are no worries about the crusting of the buttercream.  I would also probably use royal icing instead of buttercream.  I just feel like it would go on a bit smoother.

But I agree with whatthedogate about practice.  Even this cake, in my opinion, is verging on mummy territory instead of pretty territory.

Ha! I agree, not my favorite design to try and replicate for sure. The bride does not want fondant but that would help. I think I’ll try the royal icing. Thank you for the replies! Wish me luck.

I like the flowers.............