Micrometer adjusting spanners work very well for me or when the glands are hard to get at a small flat blades screwdriver can be useful.
If you want to make something that cut a narrow strip off some 20g or 1mm steel sheet. Hacksaw a slot across the end of some 3/8" rod. put one end of the strip into the slot and wrap it 1/3rd way around the rod then bend back at a suitable angle to make the head. Repeat with a 1/2" rod. The glands don't need a lot of force so mild steel will do but you could use annealed spring steel if you wanted.

J
Edited By JasonB on 22/05/2015 20:03:02