2371: a Cray supercomputer; the black 'seats' are the
low-voltage power supplies, the aluminum ribs are support
for the liquid-cooling plates, and the center hole of the cylinder
is where the interconnect wiring is handled... by very slender
women who can fit into that tight space.

2374: maybe a tool holder for a lathe? Bits clamp to the flats,
and the big hole is for bolting the holder to the tool sled.

2375: homely homebuilt boat anchor?

2376: either a kind of lamplighting tool (on the end of
a long pole) or maybe some kind of torch (but I see no way
to attach any windshield).