My skills on a CAD program are not good enough to do that, if anybody else is good enough I can do the printing if they send me the stl file. The one I removed from Chinese cap was really soft and exactly the same as Honda original so if you can wait for yours to be delivered from China which takes about 3-4 weeks that would be the quickest way. Don’t know of anyway of softening the old rubber though my cap leaked the same way as yours with the same effect on the paint! I only filled tank to half way for the first few weeks and the rubber softened slightly with use as it had stood for years with no petrol in tank.
Garyb