Agree the 24V psu and TB6560 drivers give very low performance and possibly lost steps under load.

You can hand make the large end L plates using a template and router with a carbide fluted end mill. Accuracy is not critical as the outline is mainly cosmetic and the holes can be drilled oversized. If you are fussy they can be the first things you remake with the machine.

Belt drive is often neater as the stepper can be tucked away. At 2010 you would usually 1:1 drive for wood and 2:1 ( step down) for aluminium.

Z axis should be sketched soon as the ballscrew location, ballnut, and stepper location at the end of the gantry all need to fit together. You also need to add the spindle plus a cutting bit to check the gantry is at the right height to give the range of movement you need on the Z axis plus clearance to machine over a vice.

1605 is often fine for Z but if you have bought the other size then use that.

Draw as much as you can before cutting anything because the details can catch you out !