I got this old, rusty adjustable wrench from my father in law. He was using as it was and had no problem that it was rusted and had no handle. It's probably more than 100 years old.
First I removed the loose rust using water and then vinegar and then the makers mark became visible. Goldenberg, an old German tool company, I think.
After rust removing and polishing, I made a handle for it from some random wood on the lathe.

00:00 Overall View
00:30 Disassembly
02:27 Rust Removal
03:49 Cleaning The Shaft
05:52 Flattening The Jaws
06:57 Replacing The Guiding Rods
09:24 Cleaning The Jaws
10:55 Making The Handle
14:28 Final Assembly
15:29 Before And After