机
=
几
+
木
:
Joan of Arc (ji) made a machine (机) that fully automatically manufactures tables (几) out of Christmas trees (木) and tests it in front of the space station (Ø1).
械
=
戒
+
木
:
Marie Curie (xi) finds a turning machine (机械) under a Christmas tree (木) in the elevator's bathroom (e4). Happily she proceeds to manufacture a ring (戒) for herself.
工
=
二
+
丨
:
Mnemonic symbol: a steel beam, since 工 looks like the cross section of a steel beam.
Gitta Giraffe (gu) is working a shift in front of the engine ((e)ng1). Her job is to melt dinosaur bones (丨) so that they can be disposed off easily. To melt the bones, she is shorting a huge capacitor (二) with a steel beam (工) which consequently heats up to a bright glow. Using the glowing hot steel beam she can melt the dinosaur bone easily.