If you're only filming something below the surface the fishtank may work, or you could try renting one of the housing at a divers shop.
later
TOm
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What everyone seems to forget is that once we look past race, religion, gender, and all that, everyone on this planet is first and foremost...
...a PERSON
However some companies make generic casings to fit a variety of camcorders within a certain size range. These are still like $300 to $500, as crazy lou said. i have seen different kinds of these housings, from a water-tight cylinder case to a high-tec plastic zip-loc bag. if you have $2-300, you could get something to play around with. try the Ewa-Marine brand housings listed on the above site.
i wouldn't suggest "making" one, only because you have such a huge investment at hand. while underwater housings can get expensive, at least they're guaranteed to keep water out. Ewa makes some $220-range ones for smaller camcorders that might work perfect.
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