a) At one point, the script described extensive damage to the interior of the ship.
Foss designed a robot device to make the repairs on board the ship in the engine room.
b) Another repair vehicle for the Nostromo in the script that was not mentioned in the script but that Foss created for possible emergency conditions.
This mechanical manipulator, The Picador, was controlled by human guidance.
c) Leviathan Engine from within showing 'Picador' at work. Chris Foss 77. from Charles Lippincott's Facebook page
d) Cobb commented "These Foss repair machines are "waldo-like"vehicle concepts developed by Robert Heinlein." (Book of Alien)
See: Alien: "Waldo-like" repair machine (1977) by Chris Foss for an exploration of this illustration with the yellow background