|Mud-Dauber Wasp Cells|
I am assuming this is the similar species the text describes, Sceliphron formosum, which does not cover cells with extra mud and is a coastal wasp ranging from Northern Territory, through Queensland and down to New South Wales.
The wasp itself is slim with a thread-like waist. Gold and black. I don't know if it stings, usually one can wave this one gently out of the way if it flies nearby.
These are the wasps that overseas are implicated in aircraft crashes, and locally for getting into the smallest holes and stuffing lawn mower apertures with mud, keyholes, car ignitions and gas system intakes. Many local farmers spend hours undoing waspish labour to get things working again.