Hi Geo,
I used a tube 2" in diameter (the tubes of glue/silicon that you load into a dispensing gun are perfect), applied a release agent, painted in finishing resin and applied the cf. Once it dried I used sandpaper with a sticky back to trim the hole in the fuse to the exact size of the scoop and glued in the scoop. I lastly trimmed off the protuding portion of the scoop with sand paper (protecting the fuse paint with masking tape).
I was very happy with the result but must confess it wasn't my original idea, one of our local F3A Jedi (John Payne) talked me through it which was incredibly helpful.
Simon