First of all sorry for the long delay, life and other interests have been encroaching on my build. When I'm not modelling my mind is usually working behind the scenes trying to figure out the simplest way to construct certain items with the least amount of effort. So, the strange above item is where the spark plug goes and each cylinder has two of them, one of either side. Seeing as I have to make twelve I wanted to do as little as possible to make these. I came up with the heat forming method to make the cylinder and cone shapes, I think the photos tell their own story.
The aluminium former and heat formed parts.
A test component is seen on top of the drawings.
A better close up of the test piece.
And a close up of the aluminium former with their respective formings.