Once the set arrived at ILM, Von Homburg was positioned in it wearing full costume, makeup, and prosthetics. Lighting was used to eliminate shadows, creating a flat image. A photograph was then taken and enlarged to be used as the painting. Welch's department treated the photograph to make it closely resemble an oil painting. Scenes of Von Homburg on the set delivering his dialog and stepping out of the set as if leaving the painting were filmed; according to Eytchison, the actor struggled with the action and Reitman did not like the effect. The ending was changed completely, eliminating the living picture concept. When Vigo interacts from the painting in the finished film, the image is replaced by Von Homburg's disembodied head floating over a miniature river-of-slime set built from foam by ILM. When leaving the painting, Vigo disappears and materializes into the scene. Another concept had him "peel" from the canvas, and another had the slime bring other paintings to life to aid him. A molded mask was created to represent his inner evil; it was worn by Harold Weed as the possessed version of Aykroyd's character.
