I'm not keen on how far the Z-axis overhangs (parallel to X). Presumably you've done that to position the Y-axis ballscrew more optimally than having it on the back, a long way from the cutter? That's sensible, but I would at the very least try and add pockets to compact the design, or add a second piece of extrusion above the existing one such that the ballscrew can run between the two, i.e. directly between the rails which is optimal.