I have built an all steel Prusa i3 frame to test its rigidity and to see if something like that is a suitable platform. However I find that it is better that the table does not move. It is clear I am better off building a ShapeOKO type frame using 80/20 extrusions and use RUMBA as the electronics. That gives me the ability to set up a single X carriage with the laser and extruder nozzle close together and the spindle on the other side. I will see about building a frame that way.