The final shot of the Dream of Dolls Dancing sequence takes place under water. The mermaid is floating and the One is sinking. I shot each character separately over a greenscreen, created bubbles in Cinema 4D, and assembled everything in After Effects.
Since I am only doing one shot with a downshooter, I put together a temporary set up with my existing materials instead of constructing something more permanent.

The acrylic sheet is clamped to the two animation tables to suspend the puppets above the greenscreen backdrop paper on the floor.

To set up the camera for this shot, I removed the central piece of the tripod and attached it to the arm of the c-stand.

The mermaid has magnets built into her derriere. A second pair of magnets under the acrylic sheet keeps her securely in position.

I shot the mermaid sideways so I could get the camera closer to her in order to have as many pixels as possible to work with.
Once the two characters were animated I brought them together in my After Effects composition and rendered the partially completed piece as a JPG still image sequence. To create the bubble effect in Cinema 4D, I imported the image sequence for use as a backdrop and constructed an invisible model of the sinking creature to displace the bubbles made by the particle emitter. Then I rendered the C4D bubbles as a transparent PNG sequence and put it together with the other elements in After Effects. A still image of the final result is at the top of this post.

In this screen capture of the Cinema 4D viewport window you can see the rendered frame at the top left. The bubbles and the puppet in the background frame are visible, but the CG character model is not.
The next step for this project within a project is to work on the sound design……