The water tank plug now made and fitted in position to have the owner okay its design and size and the make the tank from the plug.

Making the bracing to be the same shape as the finished water tank to make the water tank the largest it can be in the given space available  

Skinning the the tank to give is finished shape 

The water tank plug in position to get the owner's okay on its design and size then make the water tank off the plug, once the plug as been coated and polished to take a moulding off the plug.

Fitting the space closely so there will be little chance of movement 

The bottom of the plug showing there is just enough room to fit the feed line in the bottom of the tank at the lowest point just forward end of the tank 

The water tank in position  a good fit in the available space.