Last year whenever I went diving I had to either stand up off the floor with a set of doubles, or haul them over to the stairs or pick them up onto the bed...big PITA plus I'd like to have a functioning back when I'm older.

I don't really have much storage space due to living in an apartment with no garage or working area.

Thus I came up with this tank cabinet...
I'm working on finishing it at the moment. It's designed specifically so I can walk inside wearing doubles, back up to this, set them down, lean them against the cabinet (it can accommodate up to 3 sets of double 130s if the cabinet is against a wall, or 4 sets if it's in the middle of a room) and get out of my harness. Much easier than getting up off the floor with a set of doubles on, or trying to sit down while wearing them.
While the main idea behind this was to help alleviate the strain of trying to stand up from the floor with a set of doubles, it is also about organization. I can potentially keep all my cylinders, regs, lights, and other gear in one spot in my apartment.
Aside from the doubles, this cabinet can also hold up to 4 single 130s + 2 Al40s (and possibly some Al6s), if I want. There's also some space for random/miscellaneous junk. Since I'll probably end up with more than 4 singles tanks after awhile, I'm thinking of making a way to attach them to the sides -- probably standing up and held to the side with bungie attachment points. Something tells me this will be a never-ending project.
I've put sanding sealer on the top part and done a bit of staining (hence the odd differences in color between the top and bottom) but haven't finished yet.
Before this project I had almost zero experience with woodworking, so my father was kind enough to help out when I needed it. Plus, since he is an architect, having the whole thing designed in CAD beforehand was a big help. Getting to what you see now took
many months, since I don't have access to a table saw or router at my apartment complex -- I just had to steadily work on it whenever I went home every few weeks or months from college to visit my parents. With the small work area and primitive tools I had to use, I think it has turned out rather well.
Fiancee's double 72s:
My double Al80s + 4 singles tanks (LP80s top row, 119s bottom row)
Singles tanks -- I built the 'cubby-holes' for the singles tanks ~10.5" square so that long, 8"-diameter cylinders would have plenty of wiggle room when inserting or withdrawing them.
3/4 view
Other side on the bottom piece for holding of reg boxes and other junk: