I have been toying with the idea of making a one in fibreglass and Jays sent me a spare cowl to use as a model. My idea is to leave most of it as is but reduce the opening to a round hole that only just clears the back of the centre hub of the steering wheel. It would then be covered to match the trim of the car. In order to do this the only thing that I can think to do this is to take a plaster cast of the inside of the cowling and then re-sharp the section that I want to change. For a one off I could then use that as a male mould. Alternatively I could then use a coating of thicknessing wax (if I can find it) and make a female mould.
One way or another I must get off my backside and decide what I want to do.