I have 2 big black plastic boxes for my sheep stuff. They have yellow wheels and yellow clip locks, you can get them in B&Q. A big one for all drenches and fly pour on that locks with padlocks at both ends of the lid. Farm assurance are happy with this. A slightly smaller one (but still a decent size) for consumables like gloves, jakoti shears, markers, lambing bits and bobs, mineral drenches. That one can lock too. They stack 1 on top of the other so I can wheel both out and have a sort out if needs be. Ear tags and taggers in a plastic tub, raddle powders and harnesses in a lick bucket with lid on.
All injectable meds are in a big wall medicine cabinet.