That is the silver addition gadget from Mark Osterman's GEH darkroom. There are a lot of much simpler ways to add silver to an emulsion, but I absolutely love the look of the thing! Off and on I wonder if it couldn't be used as a hook to tie emulsion making into the Steam Punk culture. Mark's emulsion recipe comes from just about the era the culture parodies. Unfortunately, my marketeering creativity totally breaks down when I start to imagine all the Steam Punk things that you could fit your darkroom with! On top of Mad Scientist culture, maybe?? The mind boggles.