Crazy as it sounds, call a large taxidermy shop. They crate and ship lightweight but fragile(relatively) items frequently. Think lifesize mount of deer all the way up to grizzly bear, and larger.
Edsel mfg makes the (dare I say it) domestic version of that shelving. Google around, and you can find a large variety of the different size pieces you want.
The kits from HD are cheaper, but if one size doesn't fit all, you have options
Not exactly a tool box, but Stanley Vidmar makes a 60" wide full width drawer cabinet that will handle the weight of hand tools, and in a variety of heights/drawer sizes