The steam vents were there to produce a forest indoors since anything realistic for shrubbery in a warehouse was unlikely. Due to lack of sight it is considered to slow down movement like a forest and provide concealment.
The steam is merely four ends of cue tips cut to different lengths and glued together after careful pulling of the ends. The bottom is small pieces of magnet that each one of us probably has somewhere on our fridge in some form of another that is easily cuttable. It provides enough magnetic force to grab on the earth magnet without holding it too tightly. It actually works quite nicely.