I don't have a large expansive collection of diesels and rolling stock, but storage is a problem. Right now, all the diesels are in their respective boxes packed in a larger box. All the better rolling stock are in their cases, packed in the same box as the engines. Although this keeps everything together, it's a pain to take what you'd like to see out, then return it later.
Where do you keep the trains that aren't on the tracks?
Where do you keep the trains that aren't on the tracks?