Casting Metal into Seashells and Casting Seashells in Metal

On another channel, linked below, I saw some interesting experimentation with pouring metal inside seashells to reveal the internal structure. I thought I might try a bit of this myself, but also in a way that allows me to cast both the inside and outside of the shell form. Here's the video that inspired me:    • Pouring 2000° molten Copper inside a seash...   Also, I'm grateful for Robert Tolone's enormous expertise on silicone casting. Take a look at his channel if you want to see it done properly!    • Save Money By Recycling Used Rubber   Part 2 of this series (making something with actual utility) is here:    • Casting Seashells Part 2 - Something Usefu...