Luckily, Lulu and I did the silicone casting on the last day when school still opened. However, we didn't get the chance to go back floor to see the result of casting. I don't think it would be a successful one though. We went through a lot of mistakes during our first casting.
We Used the pipe cutter to cut the pipe first.
We didn't know that we couldn't use the mold core demoed in class and we didn't get enough time to 3d print one, so we used the broken core to give a try. (After receiving Kari's helpful email we knew that we could use a dowel) But we forgot to hot glue it on the top so it popped out during vacuum degas.
Also, we don't know why the silicone liquid popped out the first time when we use the vacuum to get the bubbles to rise. While at the second time we used the vacuum, it's good - no liquid went out.