I've been playing around designing accessories that can be snapped onto the rim of a 5 gallon bucket. There are many varieties of buckets so I picked one that is pretty common in N. America; the ubiquitous Home Depot "Homer" bucket manufactured by Leaktite Corporation (https://www.leaktite.com) who, it turns out, also makes buckets for Ace Hardware and True Value among others. This design may fit other brands of buckets, but, then again, it may not.
Once you have the basic profile that snaps onto the edge of said bucket, the sky's the limit in terms of what you can make it do. I'll be posting some variations on the theme as time permits. I've got quite a few.
This particular iteration is called the BevCom, an acronym for "beverage" and "combination". On the outside of the bucket It is sized to accommodate a 12 oz. aluminum beverage can (which coincidentally, is the same diameter as a can of WD-40!) and on the inside it has a number of holes that will house a few tools. The hole sizes are a work in progress, and I include the .f3d Fusion 360 file if you want to customize them to fit your tools.
A word of caution: depending on the weight of the objects stored in the BevCom and the contents of the bucket, be careful when you pick the bucket up. An empty bucket and a heavily loaded BevCom might tip over. Ballast is suggested.
This is printed in PLA but might be more robust in ABS or some other filament. For strength it's printed on its side with support (including 4 layers of dense support) and 50% infill. 
https://www.youtube.com/watch?v=_iDAyY7Mn3s