The next thing I needed was a motherboard tray. A PowerMac motherboard is not ATX or any other standard you have heard of and so the screw mounts for the motherboard would be in completely the wrong places. Furthermore, the back IO ports and PCI slots were wrong as well.
Therefore a motherboard tray would be needed. The choice was ATX or mATX. Hours were spent on forums looking at other peoples builds and seeing how ATX and mATX fit inside the case with all the other parts such as power supply and hard drives in different places.
In the end I opted for ATX, since the motherboards are more common and offer better upgradability. I could only find 1 online store in the UK that sold a tray. Kustom PC’s sold a Lian Li tray for £27 and £7 postage. There was only 1 in stock so I had to buy it.
I also wanted an ATX motherboard which I could mount to the try for testing. I headed over to eBay and found an Asus one for £10 that may or may not have been working.