Joe asked if I could do an owIdunnit on the opening doors in my Port Elderly thread. I think that it was Joe - apologies if I'm wrong. 
Obviously the first thing to do is build the doors . . .
These are laminated from Evergreen Metal Siding 4529, but you could use 4528 or 4125. There are quite a lot of them in the range. The second laminate is plain 2 mm styrene with a hole cut in it to take a piece of 1 mm lead flashing. Then two pieces of 3 mm to hold the flashing captive and to provide an anchor for the pull. The lead is to give the door some low down mass to create a pendulum effect and to smooth the travel.
Here is the door in place. The guides are popsicle sticks glued with PVA. A second arm is made from 3 mm styrene. The push/pull rods are 1 mm piano wire. A standard aero-modellers' servo will provide the muscle. The servo is mounted in its bracket which comes supplied with ESU servos available from www.SBS4DCC.com The different attachment points give a mechanical disadvantage which allows many times the travel by the door compared with the small travel by the servo arm.
This door is the other hand. A copper bus has been installed to provide power for the fluro lights on the outside. It plugs into the layout board through the space at the bottom. The floor only goes halfway across to allow clearance for the turnout servos below. A single steel wire has been strung to hang the servo cables out of sight.
From the outside ▲
The finished article ▲
Some detail to embellish it a bit. 
And a short movie, showing it operating . . .
The servos are controlled by a Tam Valley Depot Octocoder ™ It's basically eight decoders on a board plus the special components needed to run the servos back and forth from their central positions.
http://www.tamvalleydepot.com/...opusservodriver.html
The Octocoder is normally used for driving my turnouts, but it has many sophisticated functions - including the ability to drive the servos really slowly - as you can see in the movie.
I hope that you found my little tutorial interesting.
I am happy to field any further questions. I've done similar doors which (a) slide and (b) swing; using the same technology.
Cheers.
