I found some really small flint rods in a hardware store. They are used for lighting torches and they are pretty cheap. I glued some to small magnesium bars, that I had after trimming the usual bar to a convenient size for my kit. Epoxy resin works well for this. For the other rods I use a helical spring to attach them to my keyring. Here´s a picture of the rod and the bar ( the coin is a quarter):



For EDC I protect the rod with a transparent tube and the bar with shrink tubing.