Alright! This picture was made for the challenge; Better bending!
I decided after watching a video of a guy floating a iron cannon ball in a vat of mercury that it would be cool to be a mercury bender. The girl in the picture is a avatar(way after Aang). She uses earth bending with water style movements to control it. The mask is to keep out the poisonous vapors. She keeps the mercury in a sealed canister when it's not being used(not shown). It is so heavy she needs to use earth bending to move it around.
The really nice looking mercury bubbles were made with the hawskmont bubble brush
GIMP BRUSH AND REFERENCE PAGE