Benito,
Try looking for PVC sheeting to cut and make a tank. Many plastics fabrication places have it. You can cut it with a table saw. If you go to the LF home page there is an article on making a sink with instructions on how to cut and glue the PVC. You can make a jacketed tank - double walled, as well as light-tight lids. If you don't have the equipment to cut the PVC the plastics place may cut it for you to your specifications.
Mike
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