Aluminium and Brass ATX Case

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Ten years ago I made a case for my computer using aluminium extrusions. I'm still using it and don't expect to need to replace it for a long time yet, nonetheless I wanted to try making another one to put the lessons I learnt from the first one into practice. Here's a list of some of the things I wanted to improve:

  • 30x30 extrusions are far bigger and heavier than necessary; I don't need a case to be able to hold the weight of multiple people standing on top of it.
  • The PCI bracket screws are partially obscured by the chassis, making it hard to use a screwdriver on them.
  • There's quite a lot of wasted space inside.
  • There's no access to the back of the motherboard while it's installed (useful to install CPU heatsinks that use non-standard backplates, or M.2 drives on the reverse side).
  • The panels aren't as quick to remove as I would like.

I also wanted to make a case in the normal orientation rather than rotated 90° like the last one. Though the rotated case makes accessing the rear connectors very easy, and helps with airflow, a normally oriented case can be made smaller, which is a worthwhile compromise for a case that I'm only going to use as a spare.

Chassis

First, the chassis. This is made from smaller 20x20 aluminium extrusions, and using rounded outside edges rather than square, so it looks a bit less brick-like.

Aluminium extrusions connected to form a cuboid. An extra three extrusions are connected horizontally across one of the sides.
T-slot extrusions make it very easy to put together things like this.

You might have noticed that there are some extra horizontal bits at the back that don't serve an obvious purpose. They are there to bolt the motherboard to. Rather than having a separate motherboard tray, by mounting the motherboard to the chassis itself I can both allow access to the back of the board and save space.

It's 520mm high, 220mm wide, 420mm deep - about as small as a full ATX case can be without compromising compatibility.

Internal Panels

In addition to the chassis, some panels are required to hold all the components in place. These consist of a rear IO panel, a front fan panel, a few small plates to attach stand-offs for the motherboard, and a u-shaped support for the PSU at the top of the case. I designed the panels in QCAD, then got them laser cut.

A CAD drawing of the rear panel. At the top is a cutout the shape of a PSU. In the middle is a hexagonal grille.
It took a while to get the hexagonal grille holes to tile exactly.

Having the panels laser cut let me integrate the exhaust vent with the panel itself; there's no way I could have cut hundreds of tiny hexagonal holes by hand. This leaves the panel stronger than if it had a single large hole with a separate grille attached.

I chose 2mm thick sheets for these panels, so they are very strong. The rear panel in particular needs to be strong enough to support the weight of a PSU.

The same chassis as before, now with aluminium panels attached to the front and back.
The black part was extracted from another case, and is the only part in the whole case that isn't custom.

To avoid the problem with the PCI bracket screws being obscured that my last case had, the rear panel is mounted behind the rear members of the chassis rather than flush with them. This requires the case to be slightly larger, but having the chassis extend out the back is helpful because it offers a little protection to cables plugged in the back.

It was really hard to get all the parts of the vestigial motherboard tray to line up. I had to put them roughly in place by eye, then place a motherboard on top, then remove it and move the parts around, then try with the motherboard again until it was all right. This would definitely not be a good way to design a case for mass-production.

Front Grille

To keep the fans safe from inquisitive mammals and their probing appendages, a grille is required. Like my previous case, this one has no fans except front intake fans, which means all air entering the case passes through them, making it easy to control dust by placing a filter in front.

A flat rectangular piece of coarse brass mesh.
The grille started life as this piece of mesh.

I chose brass, as I like the way the combination of brass and aluminium looks. To be sturdy enough to resist poking fingers, I got mesh made of coarse 0.63mm wire. Even at that size, it's not stiff enough by itself, so I folded the edges over and soldered the corners together, greatly increasing its rigidity.

The brass mesh, but now the edges have been folded to form a tray-like shape.
It was pretty easy to bend into shape.
Close-up of one corner of the grille, showing that the wires are soldered together.
I would like to say it wasn't me who made such a mess of the soldering, but it was me.

The shape of the grille makes it able to hold a bit of reticulated foam to function as a filter. I also added some screws sticking out of each side of the grille. These clip into the slots in the chassis members, holding it in place securely while still allowing it to be removed fairly easily, though it requires a screwdriver or spudger to lever it out.

The grille again, but this time fillped upside down. It's filled with a sheet of black foam.
The screws down the sides not only hold the grille in the chassis, but also serve to hold the filter in the grille.

Switch

Rather than having two separate switches for power and reset, plus a power LED, I got a 3-position rotary switch with a built-in LED to serve all three functions at once.

A selector switch, made of metal. Wires of various colours lead from it to connectors that will fit in a standard front panel header.
I added some lovely coloured wires and twisted them together, so they look like a bendy stick of rock.

I don't need to access the switch very often, so I put it on the back of the case.

The switch installed in the case. There are two symbols above it - a circular arrow to represent reset, and a power symbol.
I scrawled some symbols above the switch to remind me which way to turn it.

Also visible in the above photo are some extra exhaust holes to the left of the PCI slots. These allow a small amount of air to exit after flowing underneath the motherboard. I don't know if this will make a meaningful difference or not.

External Panels

Lastly, panels are needed on the outside, otherwise it wouldn't much of a case. I decided to use aluminium, as it's cheaper than the carbon fibre I used last time, and it matches the aluminium of the chassis. To make it a little more decorative, I glued some superfluous brass parts to some of the panels.

The completed case viewed from an angle that shows the left and top panels, and the front grille.
A bit of polishing and now the brass shines nicely.

To attach the panels to the chassis, small steel patches are glued to the panels, which stick to magnets screwed to the chassis. Half the panels have small brass handles so they can be pulled out. The other panels need to be pushed out from inside.

A close-up view of the inside of the case, showing several magnets sticking to steel plates attached to the panels.
There are a lot of magnets inside.

The panels are all solid, forcing air to flow over hot components before exiting out the rear. If there were holes in the sides, then air could flow straight from the intake out the holes without cooling anything. Holes also allow noise to escape, with holes in the side being the worst, because sound can travel directly from them to the user's ears without having to go around any corners. The top panel does have a few holes at the back though, to prevent the space above the PSU from becoming stagnant since there was not enough room to add any holes in the rear panel there.

The completed case viewed from the rear.
It looks quite presentable even from behind.

The external panels are all 1.5mm thick, which is thicker than commercial cases normally use (not that there are any commercially available cases made of aluminium any more). This makes them nice and sturdy, which is good for the ones with brass glued on, as any flexing could cause the glue to fail.

The right side of the case, with the large brass Hilbert curve clearly visible.
Brass squiggle.

If you're wondering about the shape of that brass part on the side, it's a Hilbert curve, which is a type of space-filling curve, which is a curve that completely fills an area. Or it would completely fill an area if it had infinite iterations, but I couldn't make one with infinite iterations because it would take infinite time to cut and I didn't want to wait that long. There's no special reason why I chose that shape - I just needed something to fill the space, and a space-filling curve was the first thing that came to mind.

The left side of the case, which has four panels in total, two of which have handles, and one of which has a small Hilbert curve on it.
It's almost Art Deco, though I wasn't aiming for that.

Being made largely from aluminium and being fairly compact means that this case is lighter than a typical steel and glass case, at 6.9kg with all the panels installed.

Components

For now, this case is only going to be used to hold a random assortment of spare parts.

The completed case with the right panel removed, so the interior is visible.
Empty...
The same perspective as the previous photo, but this time it has a PC built inside it, powered on so there are a few RGB LEDs lit inside.
Full!

Plenty of room for modern gargantuan graphics cards. The middle case fan is lined up with the CPU heatsink, with the intention of ducting it like the previous case, but that's not possible with the oddly rotated heatsink that's in there right now.

The left side of the case with the middle two panels removed. The reverse side of the motherboard is visible inside.
I brushed the outside of the panels by hand with a little steel wire brush, so they are quite shiny without being too fingerprint-magnety.

The rear of the motherboard is mostly accessible. One part in the bottom left is blocked by one of the plates that hold the motherboard stand-offs. That part can't be removed without losing compatibility with µATX motherboards, though it could be trimmed down a little. I don't have a motherboard with any M.2 slots on the back, so I can't tell if they would be accessible either way.

And that's it. I'd call it a great success, but I'm biased.