This can yield photographic quality shaded projections with an extremely high resolution. Some theatre supply houses can even custom-etch patterns from photographs or negatives, though this tends to be expensive. Generally, gobos are placed in metal gobo holders and inserted into the instrument via a special slot. Sometimes old ellipsoidals do not have provisions for a gobo holder, therefore the gobo must be wedged into the instrument's aperture. This tends not to be optimal, because the lack of an externally accessible holder makes it very difficult to move and adjust the image.
Several companies produce gobos, often times the same companies that sell color media.
Catalogs of patterns are available, usually free of charge, from these companies or their distributors. A striking scene from the 1995 WPI Masque production of Ray Bradbury's Fahrenheit 451 . Interesting effects can be obtained by combining gobos and multi-colored color gels. Pieces of different color gels can be cut up and taped together to form a single, multi-colored sheet of gel. When combined with a window gobo, an interesting stained glass effect can be had.