How to make your own digicam underwater housing? using see-through

How to make your own Digicam Underwater Housing? Using See-through plastic?

Is there any Idea? How to prevent moisture?

well you have to silicone the living crap out of whatever you put together- and you need to make allowances for underwater pressure if you intend to film in deep water with it.
what is your idea to film here- are you going to activate the camera first, then place it in the waterproof box?
I guess I would use plexiglas- create a cube that your camera will fit into- use some weather stripping on the door side so that rubber butts up against rubber weather strip. the rest of the cube I would silicone all of the pieces together- probably even wrap the outside with fiberglass cloth and resin- leave the view port (window) clear of fiberglass resin. figure out a good way of closing the door so it will not come open. and you should be set.