Other than laser marking, is there a relatively easy way to put labels on my tool holders so I know which tool# they are? Waterproof labels? Will that throw off the tool balance and wreck my spindle? anything like that? How do you all do it?
Why "other than" ? They are cheap as heck, fast as heck, versatile as heck, look great and useful as snowshoes and a thick coat in a blizzard. Laser markers are super. You can even mark personalized rocks to throw at your lazy workers.
But if you want to do things the hard way, there's electro-chemical kits that do a very nice job.
Two steps below that are those buzzing engraver things that always look like some toothless two dollah ho down on san pablo marked your tools for you. But everyone has their own ideas of what's important, so .... they do make marks on tools, which you can usually sort-of read.
One shop I was in had a bunch of cat 40 tool holders powder coated to keep track of which machines they went to. They looked good for about 3 months and were indistinguishable un powder coated tool holders in about 18 months.
Laser marking is good if you can get a more expensive machine that can do deeper engraving without taking all day. But in my experience, for frequently handled tooling, shallow laser marking sucks and is illegible before long.
If I was going for permanent markings I'd go with the normal deep rotary engraving - twice at 180° so you have a minimal effect on balance if you're at high enough speeds to be worried about that.