Thanks for the suggestion, but given the complexity of the individual elements of the tunnel and the modules you would have to design an internal structure that would fit and support the entire ring, so you would have to redo the model by inserting the internal armature from the beginning. Passing a wire inside would probably only increase the weight without giving any real support. Believe me, it does not scare me the amount of work but if work eventually works.
Something like this, made of cardboard.

Thanks
Nando
Something like this, made of cardboard.

Thanks
Nando