Northsider

Yes, that's a Manx half brake. Do you mean yours have curved roofs? Not much will go round a radius that tight, except (thin) sheet metal, or thin strips of material filled and sanded back. What is your cunning plan?

What scale are you working in? Admittedly 15mm/ft makes the curves gentler, but I've managed to create duckets: superglue the flat section first then fix the curve bit by bit.