A good friend of mine made an aluminum tack box for me last year. Between the two of us (he is not involved in the cattle industry) we spent a lot of time planning and designed what I think is a really cool box that a lot of people have commented on.
A few of the features are:
-A small drawer (4 inches high I think) to put pens, pedigrees, snacks, scissors, clips (and everything else that always gets dirty or lost) in.
-A 6 inch high drawer to put combs, show halters, show harnesses, etc in.
-Large drawer that fits feed pans, water buckets, wash stuff, cans, spray bottles, etc. The 3 drawer design keeps everything organized and easy to access.
-Large bottom that can fit two blowers or one blower and a clipper box (or two depending on the size & shape) plus anything else you need to pack.
-The bottom row on the door only fits cans but the rest fit large cans or spray bottles with a sprayer on them.
-The best feature in my opinion is the roller drawers. That was his idea and now I wouldn't have anything else. They slide really nicely and also have a locking feature so that they self-lock if you pull them fully open or fully closed which is nice. (Not really sure how to explain that better).
-I don't really use it much but he put a white plastic piece on the side that works well if you want to tape a poster or flyer to the side of the tack box.
If we ever make another one he is going to put the wheels inside the box because they stick out on the back which makes it take up more space than it needs to and a blower should still fit with the wheels inside.
The best advice I have is think it through really well and start with a good plan. Also consider that wood may get pretty heavy.