Material for watertight coating of underwater bioinspired robot

Hi All! I'm working on the realization of an underwater undulatory lamprey like robot and I'm now working at the realization of its coating.
What i need is a material that could be easily worked, modelled and sticked. Moreover the coating should be easily removed and placed in order to recharge batteries and adjust any damage. The robot is 1m long and the cross section in elliptical and with a max circumference of 45 cm. Any suggestion is welcome Thanks a lot to everybody Guido
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