In addition to the table-top Moonbase model larger individual buildings were built for close-ups (and explosions, as in Force Of Life, War Games and other episodes). The buildings are approximately 1/24 scale. None of these correspond to the buildings of the table-top model. (See the continuity guide)
The individual buildings had windows that were illuminated by internal lights, unlike the full Moonbase Alpha model which used reflective tape.
Filming the model buildings. They are on the studio floor (the camera is in a sunken pit). Cut out photographs of lunar mountains are placed behind. Cut outs are easier to move and store than 3-dimensional model hills.
The shot as it appeared on screen, in The Metamorph
Most of these buildings are in scale with the large 44"/112cm Eagles (about 1:24 scale). The models were wood boxes with styrene sheet (plasticard) and detailed with rectangles of styrene and a few kit parts. They were rearranged from shot to shot, so these four buildings appeared in many different places. See episode shots. Based on their shape, we'll designate them (left to right here) "r", "I", "L" and "D".
In these shots from War Games, it's on the left in the first shot, and on the right in the second.
Above: as it appeared in the Space City exhibition. Below: photos from Alpha:2014 convention
Behind and inside the building: light bulbs illuminate the windows
Below: photos from London:2024 convention
Contents copyright Martin Willey