Once they've been in the oven paint the buns.
The crosses and bases will already be the right colour but add some orangey brown to the tops.
I also painted on a little varnish to look like the glaze.
Note; the salt dough expands slightly in the oven so flat edges don't come out so flat.
To fix this just use some sand paper to file them flat again.
This is something I had to do with the bottoms of the hot cross buns.