I've never turned a Cambridge, so I may be way off base. It appears the Cambridge is a really gussied-up El Grande, and if that is the case, the roller ball section and tip from an El Grande might screw into a Cambridge barrel. You would then have a plastic "section" rather than a metal section. If all this works, you would be confronted with finding an El Grande roller ball section/tip. I've been looking for theses for over a month with limited success. I've learned I could have one specially made form silver - which would be nice but costly.