How about Adjustable Parallels or Screw Spacers (which are an internally threaded tube/circumferential clamp with an externally threaded "plug?"). I have kept two sets of Adjustable Parallels in my toolchest since my apprenticeship days. I usually make up Screw Spacers in sets of three.
Another (non-adjustable) device of great utility is collections of 1/2-hard strip (usually 301 CRES left over from jobs that require it) is (slip-form) rolled to various diameters such that they fit in my lathe chucks to provide a lathe-chuck parallel for parts that do not otherwise "fit" when turning. For small (4 inch/100 mm) chucks, a set of 5 in each width will suffice. Larger chucks may require a dozen or more. I keep them in ditty bags (cloth draw-string bags such as hiker's and climber's use) so I can find them.