very little difference in my pronunciation of the initial sounds of all five words

Well, you may have a point ... which is perhaps why the author chose "caliginous", which is not consistent with the image of the Tin Man, instead of "concatenating", which is. He went for the sound over the sense.

Hey, how about

"You clinking, clanking, clattering collection of clacking ...... junk!"

Dictionary.com clack v. intr.
1. To make an abrupt, sharp sound, as in the collision of two hard surfaces.
2. To chatter thoughtlessly or at length.
3. To cackle or cluck, as a hen.