Right, after thinking about a first mechanical setup I decided to build up a cheap rig with 4 pvc pilars and a to stabilize them with welded 8mm galvanized steelrods. Well, sure.. they will be melted away by saltwater corrosion soon. But for an first attempt and to learn more about it should do..
the baseplate where later a transparent box will be placed. 8mm galvanized steelrods welded together with steel angel from IKEA. + to protect the metal from agressive seawater i later will paint it with brunox for a bit of corrosion shield.
Fixed aside with rubberjoints to the pvc pilars.
OnFinally all screwed together.