is how I read it.
Honestly, the first thing I'm thinking of trying @Slidewrights coarse diamond rasps on is shaping cork or densified foam, on the notion that it's less tearout than a rasp and possibly less grit fallout than ordinary extra-coarse.
You can also simply wrap any flavor sand paper strips around and over the diamond rasp. These could also be printed without any diamonds and then you could use PSA sand paper strips....or PSA strips of velcro for velcro sandpaper strips.