Hi there! I used Pringles can the other day as a mold. I cut the bottom off and that end of the can became my top of the mold (I hope you understand what I mean ))) I cut a piece of grease proof paper and just put it inside the can so it overlaps a bit inside. Then I cut another piece of paper, placed it on the plastic lid and closed the can with the lid (that piece of paper was just to ensure soap doesn't leak out of the can.) So the end with the lid on became the bottom of the mold ) When it was time to unmold the soap I had to tear off the can and I noticed that it was lined with the thin layer of plastic on top of aluminium lining so I guess it would not come to contact with the aluminium part anyway. Today I made another batch in Pringles can and I still lined it with grease-proof paper as it just makes it easier to unmold. I will try to save the can this time