I have built a dozen or so 3D printed machines including lathes,mills carvers and duplicators for a variety of materials and each improved drastically as I learned what I could get away with and what the limitations of each machine would be being made of plastics.
This machine would make use of all the combined knowledge accumulated and produce the best that could be gleaned from previous designs. This machine uses a gantry design for the z axis, supported by two pylons at each end which allows excellent rigidity for the tools being used. The gantry pylons are joined with steel rods that the z axis itself can be moved on if needed and solidly supported to the base with ever widening pylons and affixed to a baseplate. The axis are also all 3 d printed as three durable blocks with a conventional 12 inch leadscrew affixed to the stepper and bearing placed throughout. I selected flat pancake steppers for this design but the axis have multimounts that can accommodate and form factor motor.
The table for this 1st prototype machine I made woefully small and can increased on the next version but was most helpful in establishing endstop switches and slot sensors for positioning. The table size will increase by 25% or more on the final machine. All the printed parts I produced from ABS and are solvent fused together to make modifications, extra holes etc in future versions. I am making files for this entire machine to be also fabricated from laser cut plastics as well as the 3 D printed stl files.
The steel rods are typical hardware store versions in 3/8 inch size and I opted for the zinc plated versions as they tend to be smoother and will not rust. All the mechanical hardware for the machine came to about 35$. I used a full spool of ABS printing this machine as it appears in the picture.
As far as best way to manufacture this machine: Still unsure. 3D printing the parts is an excellent way to allow individuals to build it for themselves, but to make a bunch...That is going to take some more serious looking into. I actually made a simpler version of a gantry setup similar to this out of wood with supporting rods and it worked well(not suggesting I would use wood). There are available options that will present themselves as this moves forward.