And I had to go with the optical fibers step (a really boring step)
They are folded in two, the loop staying on the outside (except for the bridge... no reason there... just forget this trick when I started it...). They remain well in place, do not escape and fill two holes simultaneously.

They are then set with a mixture of white glue and black paint.

The fibers are then grouped to warm white or red LED, inserted into tubes (evergreen or recycling of body pens or felt pens).
The white / red allocation is made like the original for the bridge, but randomly elsewher as it was too complicated to do, and besides the right side of the studio model was less detailed and included only very very few fibers (that was the left side that was filmed and then the image reversed).

The tubes LEDs are painted in white to enhance light diffusion inside.

then covered with black for light leaks to the outside.

For the bridge, I had to make some adjustments.

First tests.