I have used edding Textile pens and Funtastics on 2 different cotton bags to add a lot of colour!
You will need - Mermaid bag Product Code: 499653
Pirate bag Product Code: 499651
edding 10 Textile Pens (1mm) art. 4-4600-10
edding 5 Textile Fun Funtastics art. 4-17-5
The bags were pre printed with the outlines so I coloured and added some shading :)