Looks like a good start. Some comments from me:
500 Watt motor seems a bit underpowered if you want to cut steel regularly. It is BLDC which should help so is it a special high torque version ?

The plates holding the pulley assembly look cantilevered off the motor body. Can they join back to the black housing to stop them vibrating?

Main black housing is quite narrow and the footprint ends up some way inboard of the Z rails. Can this be widened at the rear or diagonal bracing added?

Think about how you will cover the rails with bellows or way covers.

Think about if you will add flood coolant and provision for a tray around the Tslot table.

Is the space above the spindle for a future power draw bar? If not make sure there is space to add one.

Make sure there is provision to tram the spindle and column relative to the table. Either a fancy method or bolted joint with shims.

Otherwise looking good.