Here’s a thought for V2…have you considered rotating one of the carrier rails? In other words, rather than have the Z intersect with the X and Y axis, it could ride on two parallel rails along one axis. The Y-axis remains as is with a stepper on each side, riding on a carriage that holds two rails instead of just one. The X-axis runs along those parallel rails with a stepper at each side. Those steppers would move with the Y-axis, but not with the X. The belt ends would attach to the X carriage above the rails and route through the rails via idler pulleys on each end to return. If nothing else, it might mean fewer parts than the current middle Z.