Hereby, I present you a proposal for the flag of Australia. It's a 3:2 flag. Next to the pole is the origin of Australia. Aboriginal sun over the red earth inhabited by the aboriginal people represented in black color. Next to the right, comes a yellow boomerang, the most iconic tool of Australia worldwide which also represents Australian dinamism. Yellow color represents Australian desert. Next to the right, in contrast against the desert, comes a narrower green band representing southeastern forestal territories. Green color also represents the wealth of the people and the abundance of resources in the country. The point of this band reaches exactly the middle of the width of the flag. All the right side of these V-shaped bands is in the same dark blue as current Australian flag which represents the surrounding oceans and the sky at night. Finally, the current southern cross constellation have 2 changes. All 5 stars are 8-pointed stars, each star point representing each one of the six states, plus the remaining territories, plus the aboriginal people, who culturally don't belong to any region, and also evokes stars in the eureka flag. The size of the 5 stars increases by 1 from a proportion of 5 to a proportion of 9, that is, the diameter of the larger star (9) almost doubles the diameter of the smaller star (5). These sizes evoke the different intensities of the stars in the real constellation.
P.D.: I have the svg file with the original design at your disposal.