The engine is fitted with a piper cross PX500 air filter so I decided to make an air box that would fit over that air filter and mount to the PX500 back plate.
I started with a filter frame mounted to a wooden bade then glued on foam to start shaping, the picture below is version 1, you can see the piper cross filter frame.

I then covered it with filler, sanded and painted before applying lots of coats of mould release wax and used it as a mould to make the air box
I was not happy with the the shape of the first air box when I fitted it to the car and it didn't really have enough height at the rear for the air filter

So I made version 2 which l think looks better and has more room above the air filter


I now need to decide if I am going to fill and paint it, take a mould off it to make a new one which will give a better external finish or just leave it as it is, but I shall try it out first once the weather improves.