Yesterday, I decided to use up scrap pillar wax from recycled church candles, So, I had a plastic pretzel holder, roughly 5 in wide X 9 in tall. The inside has swirls and the container was cylindrical shaped. I do use metal molds, but once in awhile, I find something odd and I want to see how a candle would look once it was made. I had 4 different layers, each had a different scent (trying to use up fo samples) . Lavender, Yellow, blue, a small layer of red. The bottom half ( or top once unmolded) of the container sort of sucked in , I discovered that when I poured the second layer. I poured at a real low temp, maybe it was just air? But the candle is coming away from the sides of the mold, so I'm not worried about the candle coming out, I will weigh the candle and post a pic. Should be interesting