it is not so hard to make it.
when you are little kid, you had played the liquid toy. there are two kind of liquid. one is water, another is oil. There is oil always up on the water.
same idea as your designing....yellow liquid could be water. the white object is oil. you only can inject some little foam ball. Then keep them in the airproof mug.
at the bottle of the mug stick the LED and screw the hole for fitting the draft tap.
Then it is done.