I created the splines for the door in Xara X.

I then took the main squashed (outer door frame) octagon and extruded it to make the tunnel.

I then took the main squashed octagon and streched copy of it to make the "ribs".

Then the pipes were just tubes placed on the side of the wall - no need for boolean subtraction.

As for the tracks - I was getting tired - I should look like a grill on the floor. Trying to think of the Alien movies where they had a suspended floor .

Will try and do some picks if I have time.

Turan