I used a cheap plastic tool box up until last Feb. when a heifer stepped on it. Now I use a metal tool box it has my bander, dehorner paste (but have yet to use it this year) tattooer ,and tagger as well as cotton swabs rubbing alcohol and gloves. The tags I keep in my office and prepare them as the calves are born . I label the tag and put it as well as the rfid tag in a snack baggie and then in my kit. That way I keep all the tags separate and do not get them mixed up as I am tagging multiple calves..
I also have a large stainless steel medical chest that has all my meds in it that do not need to be refrigerated, if I have an animal that is sick I grab my chest and I can takes it's temp and evaluate it and I have all that I need to treat it..It comes in handy when you get a cow locked in the chute,,you can give it the complete cocktail of meds without having to run back to the house.