Scouting

Hello. i am looking for some advice and a blacksmith seem the best person to ask. I am gathering materials to teach my daughters girls scout to make fire. How difficult is it to make an old file into a striker for flint and steel? I need to make or have made 13. 12 for the girls and one for me.Could i just take the rough edge off or do i need to do some thing else to it? Thank you for any help.