The Troll Cross, or Trollkors, is symbol of protection against malicious magic. It is often thought to be an item of folklore, but there is no archeological evidence of it having been worn as jewelry. That appears to be a a more recent folk magic tradition. The Troll Cross has a strong resemblance to the rune Othala (Odal). I like to think of its protective power as carrying home, not the building, but the feeling of place, with you wherever you go.
I forge my Troll Crosses on Friday (Freyr or Freya's day). I chant into them runes of home and protection.
My Troll Cross pendants are hand forged from steel. They are given a protective coating by being heated to 1000 degrees and then dipped in beeswax, giving them their beautiful black patina.