I live in a small apartment, and as a consequence I care about every cubic centimeter occupied by stuff in my house. I wanted to have a small desktop computer, but none of the computers I found was satisfactory. I did not need a lot of computational power, I rather wanted something quiet, I thought an Atom would do fine (and actually it does fine). I did not want a CDROM bay but I wanted space for more than one harddisk. I hate the fact that consumer computer cases are still designed around the CDROM. Why? Nobody uses those anymore, really. I decided to build a computer case free of unnecessary stuff, small and tidy on the inside.
I heard too many stories of failed hard disks and I really wanted RAID. RAID 1 looks a bit wasteful to me (you have 2 drives and use them at the capacity of 1) so I thought RAID 5 with 4 drives would be nice instead (4 drives used at the capacity of 3). Incidentally, the motherboard I selected, Zotac ION ITX-G, also had 4 SATA connectors.
By-the-way, this is not a solution if you want a cheap computer case.
I have chosen aluminum as the material for the case, at it is light and thermally conductive. The design is very simple: two metal sheets, bent in an U-shape. 2mm sheets are more than enough. If I had to do it again I would go for thinner, the only problem is that I wanted sunken screws and if the sheet is too thin there is nothing for the screws to sunk into. I estimate though that 1.5mm might be ok though. The case is as wide as a hard disk. The hard disks are screwed directly into the two lateral sides, giving more stiffness to the case.
One of the first difficulties I had was that I did not know how the metal would bend. The assumptions I made turned out to be wrong and I had to redo half of the case. I would like to share with you what I found out. The aluminum bent very well, I thought there may be problems there with cracks appearing on the outer edge, but that was not the case. I'm not sure what alloy it was though. If you need to make one of these check with your machine shop. One advice I can give you if you want to try this is to make the first half, measure it and then correct in the second half everything that is necessary to make it match the first.
What I expected when bending a piece of metal would be that on the outer side of the bend the metal would lengthen and on the inner side it would shrink, possibly in a balanced way so that more or less around the median, the length of the metal bar would remain constant. This is not what it happened! It turns out that the inner side of the bend remained almost constant in length and the outer side of the bend lengthened, thinning the material. (I found this by taking a picture of the section and essentially measuring the section of the bend, we know that the volume of material has remained constant, you can do the math from there).
Doing the rest of the design, while not a piece of cake, is reasonably straightforward. All you need to do is find datasheets for hard disks, motherboards and power supplies and collect the dimensions and screw locations. Unfortunately I cannot find anymore the datasheets that I have used, I remember for the disk it was a Seagate model, but if you want you can use the drawings in the included dxf.
For the back plate I decided not to use the one that comes with the motherboard, because that is (stupidly) larger than the board itself in one direction. Unfortunately that makes my design motherboard specific :(.
The hard disks contribute to the stiffness of the case in a nice way, for the rest of the mounting I used small wooden blocks that took the screws in quite nicely.
I was hoping to run the CPU/GPU without cooling. Maybe that is possible with the newer models, but I had no such luck with mine, mainly because of the ION video card. The next thing I considered but not really tried was to make the large PSU fan draw air from the CPU/GPU heatsink through some sort of pipe. That would result in slightly heating the PSU but since it's not under heavy load anyway I guess it would not matter. I replaced the normal heatsinks on the CPU and GPU with a larger one. Some drilling was necessary. Fortunately the motherboard had 2 holes to allow the mounting of the new heatsink. I had to break one of the holders of the original heatsink to be able to mount the new one. There goes the warranty of the motherboard as well... .
I used a large PSU, as they seem to be cheaper and better. I specifically wanted one with a large fan as they tend to be more quiet. Power was not an issue as this computer only sips power (well, compared to other desktops anyway). I cut out the unnecessary wires and shortened the rest (so much for warranty...). Some advice, if you do this it is very convenient to insulate the wires with thermal shrink wrap.
All screw holes should be chamfered at 45 degrees, 1.5mm deep.
Some afterthoughts:
For a first try I would say I did well (I had no previous experience with any metal works) but I did make a few mistakes:
What I like about it:
I attach here the design files from various stages of the design.
The modified one is not what I actually made, but what I would make if I had to do it again.