Getting a Duplicate for the SteelworxBurg Wächter Cage's key?

Does anyone know how to get a duplicate key made for my Steelworxx cage? Preferably in a non-rusting metal. Currently, my fiancée wants me to wear the key inside a necklace. However, humidity builds up inside when I shower, and that caused the last key stored there to rust. So ideally, I want a copy made from aluminum or stainless steel. Any thoughts on how to get this done?

Search for a traditional lock smith nearby. Stainless steel might cost more but is doable. I wouldn't suggest aluminum though; it's too soft.