The most difficult part of adding the paper clay was the two leftmost tentacles because they are touching and very elevated in comparison to the other two tentacles. I had to be very careful in adding clay in these tight crevices. However, after I had cleaned up the paper clay surfaces and built up enough clay to the highest tentacle, I added registration marks so the two parts of the mold would be easy to tear apart later. Next, I cut up sheets of foam core to create a sealed box where the silicone mix would not be able to escape out of the side or bottom.  To ensure that the box was secure, I added multiple layers of hot glue around the edges.