given that you are already printing a hollow model - I really don;t understand what the right hand image is showing ?

And when you say you open the top and bottom - what do you mean ?
The top and bottom are already open.

What i would do, is to print two of the sections with a hole along the 'top' or 'bottom'.
Then when you glue the ring together, you have two holes: one to feed the cement into and one to let the air out as the ring filles up.

So I think I need more pictures to understand the problem, as i can't see one.