Try inverting your pot and using the bottom to reshape the disposable tin. Cut off the excess so the new rim is maybe an 1" high and perforate the tin bottom. Then slide it into your pot, adjusting to fit as needed. Yes, push it to the bottom of your pot. I think I used a "grease pot" for this one, but I have also just made a small coil or "w" shape from a piece of aluminum can wall and just sat the foil muffin cup onto it and steamed muffins in a Vienna sausage can pot. It is amazing what can work...