Modern armies run on fuel. And that means fuel trucks to carry the important liquid to the vehicles in the field. Roco Minitanks makes an accessory set with a little fuel pump and fuel barrels. I mounted one on a sheet of styrene plastic. I used styrene that has a wood board pattern so it looks like a floor of a truck or even planking or the floor of a room. The plastic is the size to fit inside a truck bed for maximum flexibility.
A specialized vehicle here. An entire engine, fuel, and other marine parts for small boat repair.