Edlund's previous work on the supernatural horror film "Poltergeist" (1982) served as a reference for the ghost designs in "Ghostbusters". Gross said it was difficult to balance making the ghosts seem like a genuine threat while fitting the film's more comedic tone. Special effects artist Steve Johnson sculpted the gluttonous, slimy, green ghost then known only as the "Onion Head ghost" on set due to the puppet's unpleasant smell. Now commonly known as "Slimer," it was not called that until the 1986 animated television series "The Real Ghostbusters". The Slimer design took six months and cost about $300,000. After struggling to complete a design due to executive interference, Johnson took at least three grams of cocaine and completed the final design based in part on Aykroyd and Ramis' wish for the creature to homage their friend John Belushi. The full-size foam rubber puppet was worn by Mark Wilson and filmed against a black background. Puppeteers manipulated the model's movements with cables.