More CoreXY Progress. Hoping to cut walls and z this weekend.
Nice, add some height difference in the idlerwheels for the cross over. Cant tell from the picture but the inner idler and x-idler need to be inline. I ran in to those issues myself 
Yea I didnt draw them like that because the assembly was easier lol. But Ive built this xy setup twice now so I know where they should be. I actually may change it again now though.
Can you add a top down look? Perspective is making the belt path off the stepper pulley to the y idler look like its at an angle. Any none perpendicular or parallel travel on belts that drive the central or y carriages will introduce trigonometry into the math.
That is except where the belts come off the corner cross over idlers. Those can go any angle you wish.