I decided to make a faux cake for the top tier because there's already too much cake for the people who will be eating it.
I cat a section of card, cut slits into the top, folded them in then taped it. You can use anything the right shape for this part as long as its light and clean.
I rolled out some grey fondant, cut it to size and glued it on. I then cut out some small shapes and strips and stuck them on with a touch of water. (water dissolves the sugar a bit and makes it sticky)
I seemed to have mislaid the process photos but I've put some final pictures so you get the jist. (I will add them later if i find them)