The "rolling" method of developing ultra-large prints is rolling the paper in a single roll, immersing it in an oblong tray full of developer and starting to unroll it, the same time rolling in in a second roll. After that (when the first roll is unrolled completely) you start all over again, and again... until the time for each bath is over... usually the time in each bath (dev, s/b, fix) is double the usual time recommended for tray processing, because the chemicals that touch the paper don't get so quickly replenished. It works really fine (I had no marks or other processing problems) if you keep rolling !! The highlights are obtained by shooting the fish on a light box (used normally to view slides). The fish were lighted with two soft boxes from the two sides but a longer exposure time was used for the light from the light box lamps to "write". Most of the negs had enough contrast to be printed with completely "burned" whites in the background without any help while printing, but a couple of them (I am not really sure why, for they were ALL shot and developed the same way) had to be printed with the help of some masks made from cardboard to hold the highlights and make sure they stay white. The exposures were really long (enlarger turned horizontally to project on the wall, paper held there with gaffer tape, exposure between 15 and 60 minutes) and I had to stay in the darkroom (safelights turned off for safety) for all that time, holding the masks in front of the lens...