Regarding screwdrivers, when I started in gunsmithing school, I was told to get Craftsman or Snap-On drivers and learned to alter them for thickness, width and parallelism at the tips by grinding on a 1" wide belt sander with the top wheel's guard removed. You want the tip of the driver to closely fit the slot and the side edges to be radius-cut so that you don't mar the counterbore or countersink at the edges. I still have some 40+ year old drivers that are a "little" shorter than when I bought them!
David Kaiser
“You can have peace. Or you can have freedom. Don't ever count on having both at once.”
― Robert A. Heinlein