This is a pretty inexpensive 4th Axis option. To be honest it falls
in the category of experimental hobby rather than any serious
work, but if you want to play around with 4 axis to see if it has
capabilities for what you are looking for, this might be an
inexpensive way to go!
Very cheap DIY 4th Axis and Tailstock. If you already have a CNC machine this is a really simple way to make a tailstock for a 4th axis setup. Was a fun project, but honestly the tolerances were not great! Could easily be modified for a more industrial setup.