Out of curiosity of Mac case design and component quality, I purchased an old, relatively poor condition Mac G5 some time ago. Most of the parts were too old to be of any use, or lacked compatibility with modern PCs, but there were a decent number of PWM fans and the case itself was very nicely built, if a little bent.

I devised a way to convert the case into an ATX form factor with the help of a donor case, with the hopes of eventually turning it into a working PC with a scratch built water loop.

As with most of my projects, this uses the bare minimum of tools to keep it accessible to DIY beginners. It would be possible with drills, high speed rotary tools and an assortment of nuts and bolts, but to speed up the process I used an angle grinder and rivet tool as well (Although the rivet tool and 1000x rivets only came to about £12, so it's a worthwhile investment to make cleaner joins in metalwork).

Step 1: Reference Images

The original paint job was a chipped black gloss with some sort of red primer or prior coat showing underneath. Despite trying to remove these with solvents, heat and physical methods to expose the original silver aluminium, I had to resort to painting over the existing layers. Since I was completely covering the old paintwork, I decided to add some flair and theme it based on the fictional Maliwan weapons company (Borderlands).

I was heavily inspired to take on this project after seeing venounan's Maliwan themed Bitfenix case

The logo and stripe positioning were largely based on malfunktionv2's Borderlands wallpapers

I designed a hexagon pattern to break up the stripes slightly, and used both the offcuts and the lines for form the patterns.

Rather than stencil the letters in, I knew I'd achieve a much cleaner look by physically sticking them to the case

Step 2: Rear IO Cutout + Motherboard Tray

The trickiest part of the build was making it compatible with ATX motherboards and PSUs. Other Mac G5 conversions have used methods like mounting an ATX PSU in the existing power supply and removing the upper partition to have a higher motherboard, or fitting it in the top where the HDD cage is. The most common motherboard standoff mounting seemed to be JB welding the standoffs to the inner wall of the case, but I actually used the existing standoffs to mount the entire motherboard tray from the donor PC onto.

The rear IO panel, motherboard tray and PSU bracket had to be cut out with an angle grinder. I worked out the positions to drill the holes on the donor motherboard tray by painting the tips of the Mac's standoffs white, placing the tray on top, pressing down, and drilling out the centre.

The rear IO consisted of several layers, but the smaller one could be removed from the back panel once the rivets were drilled out, allowing it to be used as a template to cut out the back of the Mac. The rear frame of the donor PC served as a back plate to sandwich it all together once re-riveted together. The order of the metal sheets was: Donor motherboard IO panel (Inside case) > Mac rear panel > Donor PC rear panel.

Unfortunately, there was not enough space to use one of the Mac's dual fan arrays since the fans were larger than the PC's, so I saved myself a lot of effort by instead using that space for the PSU, adding a reversible bracket to the inside and a second back plate to the outside (5 separate layers of metal at its thickest point). Rather than rivet the PSU bracket, I used M4 screws to allow it to be flipped over, although given the lack of venting, the PSU may be one of the main sources of exhaust ventilation and require any fan intakes to face the motherboard.

One thing to take note of is that the motherboard will be in an upside down orientation

Step 3: Water Cooler (Optional)

This step will undoubtedly vary depending on how you choose to cool the CPU.

Since the PSU was overhanging the CPU, I needed a very low profile cooler, and I decided to make one from an old car oil radiator. Since I had no way of welding a frame or attachment points to the case, I instead made a riveted bracket with tabs to attach it to a vertical strut (A design feature I later removed to simplify the case). In the end, I just used the top and bottom portions of the frame I made, and used the ridge around the top of the cooler as a cantilever, with the ridge being the fulcrum, the foam layer on top being the load, and the screw holding the bracket into the motherboard tray as the downward force (See final step's photos for a better look at how this worked).

The attachment points were simply a pair of steel male 1/2" to female 1/4" reducers forced in through the aluminium openings until they carved their own threads, then removed, sealed with epoxy and re-inserted. My plan was to re-purpose an old fish tank pump to move water through it, but since I wanted a silent build and integrated pump/reservoir systems are so cheap anyway, I decided to scrap this idea too and just buy the parts (Also, the pump ran at mains 240v which would mean an additional power cable going into the case).

Step 4: Front IO Panel

After some thought I decided against re-connecting the existing IO, as this would need a lot of re-soldering, and it had pretty outdated connections anyway.

I used a spare 4-port USB array from my Corsair 600T and fashioned a small aluminium plate for it. After widening the existing power button hole, I could fit in a 16mm illuminated momentary push button, which had a ring nut to clamp the plate and case together with the button. Unfortunately the version I got was falsely advertised as a 12v (They cheaped out and didn't use resistors) switch, and blew as soon as I hooked it up to my PC's 12v fan controller. Luckily it was a relatively simple task to hammer the switch out, remove the LED and drill a hole in the back, to which I can add an LED of my own choosing (I plan to make it an RGB switch).

Step 5: Painting the Case

While I don't recommend pound land for paint durability, they had a chrome wheel spray paint that almost perfectly matched the original aluminium, so I used that as the base coat.

I masked off the DVD tray, the stripes down the sides, then added my hexagon cut-outs by applying PVA to the paper and pressing it down to spread the glue to the edges, then masked off each section in turn.

While I had gloss navy blue left over from my Mjolnir Armour, the other two colours had to be custom mixed from acrylic. I used a ratio of about 5% PVA, 20% acrylic and 75% water to give the paint some resistance to chipping and allow it to be airbrushed on (My airbrush struggled with this mix, so I watered it down slightly more after the first coat).

While it may have also been the acrylic, the PVA seemed to make the paint almost "stretchy" when I was removing the stencils, so the orange hex pattern looked a lot less tidy. I'd advise trying to complete it with spray paint cans instead.

The final stage was to add the letters, which I stuck directly on rather than stencilling. They were initially almost perfect, but I had to cut them out again where the paint bled and stuck them to the newspaper, so use something like a blue-tack standoff when painting them (I did this for the orange triangles in the "A"s, which worked perfectly).