Bathyscaphe - a Cartesian diver

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This is an approximation of the famous bathyscaphe Trieste, that set deep diving records. It is meant to be used as a Cartesian diver; put plastic foil or bits of air balloons over the openings of the 2 ballast chutes on the bottom of the model and secure them tightly with O-rings. Buoyancy can be adjusted by putting lead pellets in the hole of the globular observation chamber. This is also necessary to make the little craft stay upright. Bits of bluetack also help in trimming. The file with the parts is basically the bathyscaphe split in half. Glue it together; the holes in bow, stern and turret should help in aligning the pieces. Just push a little piece of filament in (1.75mm). Add details like the motor nacelles and the vents. Of course you will need a large bottle or vase with a wide neck opening (almost 3cm) to make it float. fill it to the brim and cover the opening with a lid or thick air balloon rubber, fixing it tightly with as little air caught under it as possible. When you depress this membrane, the increased water pressure will push in the membranes on the ballast chutes of the boat, reducing buoancy, and it sinks slowly. As soon as you release the pressure, it rises again.