For the models that I do not have enough shelf room for, I simply store them in large moving boxes. They can then be accessed pretty easy, moved around pretty easy, and stacked at least three high in most rooms. Each can easily fit more than 25 typical kit boxes if you pack them right, and then box them by category for easier searching later on. This picture just shows the ones I have here in the room, not counting the boxes I have stacked in the closet. My goal at SOME point, is to have massive storage racks like I have seen others have, but those are expensive, and these boxes are around $3 at a U-haul or box store.