How about these....

Microplane Rotary Shapers

You could make a carrier to take several of them in a row - a 10 / 12mm threaded bar with spacers trapped between nuts easy enough to make up. They're fairly expensive but good quality.

Axminster have them in stock but a trawl of ebay might turn up something cheaper.

Microplane Rotary Shaper Replacement Blades - Drum Sanders - Abrasives - Fixing, Gluing & Finishing | Axminster.co.uk