Olfa Circle Cutter - from 1cm up to 15cm Diameter - Adjustable Rotary Circle Cutter - Comes with 5 Extra Blades - Ideal for Paper, Vinyl, Thin Fabrics, and Leather, CMP-1 :
Fabric Circle Cutter 18mm | Hobbycraft
Olfa CMP-2) £36.94 - Olfa CMP-2 Heavy-Duty Circle Compass Cutter