My first milling operations were carried out on a lathe with a milling cutter in the chuck and an angle plate and single axis slide mounted on the cross slide, it's fiddly and far from ideal but got a lot of small jobs done to the required spec with the only equipment I had.
I progressed to a spindle driven vertical milling attachment which allowed me to use the lathe cross slide as a table, it took quite a lot of work to adapt it to fit my lathe and rigidity wasn't great but it did some good work and was all I could afford at the time.
I'm sure a lot of the work these stop-gap measures allowed me to complete was "Impossible" in the eyes of a man with the ideal machine for the job, the correct machine for your job is the one which you have reasonable access to which can be made to complete the job to a standard you are happy with in a time you can put up with ;-)

- Nick