A piece of Ali' angle was suitably cut into 2 sections to make up the Stepper Motor brackets for the X & Y (or A &

, and was milled out to accept the Stepper shaft and also drilled for it's mounting screws. A couple more milling operations gave it the required shape for mounting onto the side uprights, and a couple of M5 clearance mounting holes were installed. Then those mounting holes were marked up on the uprights of the printer frame, and drilled/tapped M5.
Here is a couple of views of the mounts in place, showing it with some GT2 belt in place and with just 2 screws holding it in place temporarily;
The other mount (essentially identical, but a mirror image)
With the belt in place, I made a quick visual check to see if I had calculated correctly and the stepper itself is aligned so that the belt will run parallel as the carriage runs from front to back. The good news was that I had got it very close, the stepper motor mount needs to be shimmed out by about 0.5mm (as measured by my Mk1 eyeball, LOL!!) with this particular belt. Here's a couple of closer pics, 1st up is when the X carriage is furthest away from the steppers and you can see the gap to the right of the belt as it goes thru the frame;
Then this was with the X-carriage in the nearest position, and even though the camera angle changed slightly, you can see that the belt has moved to the left slightly (about 0.5mm);
Here's a pic looking up from under the X-carriage
I also have worked a little on the belt path across the back of the printer. There's still some work to be done on this, but this is how it stands at the moment (this part has been un-mounted in order to photograph it, normally this is firmly attached at the back of the frame, I forgot to take a snap of it in-situ);
There are 4 ball-raced, GT2 pulleys mounted on long M5 grubscrews. The 25mm box-section has been drilled & tapped M5, the outer pulleys do not need precise drilling as the parts of the belts that run on them do not have to remain parallel. But the inner pulleys are more critical. The inner pulley mounting holes were drilled at exactly the same distances as the the X-carriage GT2 bearing pulleys, and as they are the exact same pulleys as the carriage uses, I know that no matter what belt-thickness is used, these will remain exactly aligned and parallel.
The work I need to do on this is to improve from the temporary grub screws holding the pulleys in place in the frame, at the moment there's nothing to stop them rotating and screwing themselves out and allowing the pulleys to come loose.
I need to get some GT2 belt, as the 2 pieces I have are from different sources and one of them is too short, so I will order enough to make both belts from, then once I have that belt I can make up the shims to align the steppers to keep the critical parts of the belt path truly parallel.
Thanks for watching,
Tim