RubiconIII says:

I once used ring folders with plastic pockets for each two or more manuals. (Some bigger sets require more than one pocket alone – sets with three big manuals for instance) I would never dream of punching holes in manuals – holes would surely tend to hit critical information like the number of parts needed for building or something like that. Also it would decrease the value greatly of your manuals. I had tried to obtain folders in a myriad of colours, so I always knew that Ninjago took up most of the dark red folder or Adventurers was in the back of the tan folder. Originally I had planned that they should stand upright next to each other forming some sort of rainbow paying tribute to all the colours of the bricks.
But alas, I parted with that system, as manuals weigh too much to be stored that way – I ended up having to stack the folders, which had to lie down in order to avoid distortion from the weight of the many manuals that can fit in one folder.
I had for some time worked in a small office, where we had a very primitive way of handling lots of paperwork – most went into ring folders or elastic folders – a small portion went into some Ikea shelf with a bottomless drawer, that allowed for a few dozen hanging file folders to be hung side by side. At some point it dawned on me that a file cabinet was the right solution for me. I’ve seen file cabinets in so many crime movies over the years – I actually felt a bit stupid not realizing, that file cabinets don’t solely belong to offices, but could also solve my problem. I guess I had gotten too attached to those ring folders and just desperately hoped I would someday make it work properly. I then researched the market and found that office apparel is always kind of pricy. I decided to search the used market, and was I surprised – there were plenty of file cabinets for sale everywhere at half or less price. I decided to go for quality, so I went with a very sturdy black metal file cabinet from Bisley. It took some careful tumbling to get it all the way down in cellar. It came with about 50 portfolio-sized hanging file folders in a handful of different colours. From the tags I could tell that the cabinet once held documents from a doctor’s office.
To my luck shortly after that I was part of arranging a Christmas fair for our local scouts. When almost closing up and getting ready to clean up after the two-day event, I stumbled upon this unsteady shelf, which I opened out of curiosity – realizing that it was a drawer for hanging file folders. It immediately spawned my curiosity to search further near and around the shelf, and to my luck I found a big worn down moving box almost full of hanging file folders. And not just any kind – something close to the best and most expensive folders – I knew that from research at that point. In that box were more than 200 A4-sized, dark green and close to mint Twinlock Diamond hanging file folders with a small box full of unused folder tags – and I got all of it for practically nothing – I actually paid twice the price they asked for to be a bit fair, but still it was close to a steal. Now I had about 50 uniform folders per drawer – all I had to do was to change the cabinet format from portfolio to A4.
Now I could empty my twenty-something ring folders one by one and put all the manuals in one cabinet. I used an Excel sheet at first to plan my folder contents and have it now as a reference to the cabinet, so that I can reach for any manual in seconds when I need it. Also I found out that I could put really huge instructions (death star and such) inside one of the drawers below the hanging file folders, thus every single instruction or manual goes in that cabinet – I really like simplicity like that. Oh, and the cabinet comes with a lock and keys – a nice feature too.
Today half a decade later I’m in need of my second file cabinet, but that’s just expansion and not really a problem. I have lots of unbuilt and unopened sets so I estimate that I could easily fill up more than half of the second file cabinet already.
Hope my story or solution helps you or anyone out there.