Sorry for derailing your thread here Wayne
As far as the dome on mine goes, these a cast from some sort of "cheapish" white metal (is that the correct term?), quite similar to the material used on the old skinny Jensen flywheels, and will buff to a chrome finish on its own...if you help it to it, with a bit of elbowgrease.
When it comes to the air flow and pressure output, when being run by the Jensen 20 here, is very low to say the least.
I was planning to build it into some sort of vertical acrylic tube water-accessory, as the minute amount of air available, could be let into the bottom, and stir some motion/bubbles in that element.
But eventually discarded the idea entirely, as i have plenty of other projects lined up.