Something to show steam, coal, and water.
pile of coals? The more coal you have the more bits of
coal show up.
A tank full of water? That goes lower/higher. Could do with a
graphic using transparent alpha in the middle. Then blue is drawn in the middle
depending on how full the tank is.
Some sort of steam tank. If we have multiple steam tank parts,
this could be shown in the parts view of the castle.
