I have been in this hobby for many years and have gone from tiny field boxes to huge and everything in between. This past year I built a field box out of a Black and Decker two piece roll around tool box. It is all plastic and just the correct size for my needs. I put the fuel pump and fuel in the bottom along with a sealed gel cell battery. Top box comes off and is used for tools and other items. Gives me plenty of room for everything and comes apart as well. Can take some pictures if you would be interested in this concept.

JEB