Tool used for adjusting square drive trimmers?

[Wade]

...like found in some of my LED watches. What tool do you use? A tiny screwdriver that fits in the square "slot" or do some of you make your own tool? Or buy one from somewhere?

Thanks.

[bruce wegmann]

With some careful grinding, I made one out of a thin flat-blade screwdriver, but I found it is easier to just buy the tool from Johansen, who also make the trimmer capacitor [yes, they're still in business 35 years later, and they still make this style of trimmer]. Five bucks or so, if I remember right...