But you said that mass displaces aether.
Matter displaces aether. Aether has mass.
We can manipulate mass at the human scale. So doesn't that imply we can control aether rather easily?
I'm not sure what you mean by easily. When a double slit experiment is performed it is the aether which waves, so in some ways we are controlling the aether every time a double slit experiment is performed.
When a nuclear bomb explodes matter evaporates into aether. The evaporation is energy. Mass is conserved. I wouldn't say we are controlling the aether when a nuclear bomb explodes but we are converting matter to aether when we do.
Where the pressure is great enough aether condenses into particles of matter. There may be a way to generate that type of pressure.
The following is an image analogous of the Universal jet.
The reason for the 'expansion' of the universe is the continual emission of aether into the Universal jet. Three dimensional space associated with the Universe itself is not expanding. What we see in our telescopes is the matter associated with the Universe moving outward and away from the Universal jet emission point. In the image above, '1st Stars' is where the pressure associated with the aether constantly being emitted into the universal jet causes the aether to condense into particles of matter.