During the holographic mastering process for large format rainbow transmission holograms the strip of holographic film that becomes the H1 hologram master must be positioned in front of the subject (3D model) in such a way that it is bathed in diffused laser light, but importantly, must be held rigidly and firmly flat against a sheet of glass. Typically, elaborate hydraulic or vacuum systems have been employed to compress holographic film during the exposure process. However this function was achieved at Australian Holographics by the construction of what was referred to as 'the camera'. In fact the camera was a very long and narrow glass box, approximately 2.2 metres long, about 12 cm high and about 6 cm deep. Inside this 'camera' was a loose piece of glass slightly shorter than the length of the camera, but around the same height.