Thanks guys
I finished the air bottles that will be mounted underneath the deck.
I took 8mm aluminium tube and to get the round ends of an air bottle i glued 4mm thick pieces of plastic on the tube ends.
I gave them the right radius by sanding them with the help of a drilling machine.
I made straps from thin plastic and painted and weathered the bottles.
The salt seawater has left a couple of traces on the bottles....
Karel