Depends on the size.
Over the years, as I acquire more tools, I keep moving to larger, newer, better quality tollboxes, and have several old ones that I inheirited from my Dad. I kept them all, and use them for different purposes.
Small, tackle-box size one for R/C tools and parts.
Slightly larger one for electrical tools and supplies.
Old one for track/racing/autocrossing tools and stuff.
Another one about that size I mounted a 12v air compressor and hose in.
I have one I use to store all my painting/masking/caulking supplies and tools in
Plastic one with lift out tray I keep in the travel trailer for repairs.
Larger heavy duty plastic one I use for ATV trips and as a stool/stand.
I have several old Craftsman roll around cabinets that I use in the shop as rolling workbenches.
In my job, I work on many different types of equipment. I have a toolbag that has the things I use most of the time, but I have several old laptop bags I use to keep specific tools for certain types of machines in - one for working on large format printers, etc. GoodWill and Salvation Army stores are great places to find perfectly good (sometimes brand new) laptop bags, duffel bags, and backpacks for almost nothing. I have a backpack I use as a bugout bag, another one I use when I go to swap meets/car shows/races, etc.