I did not test it on my lathe but the goal, as a mechanical exercise, is to cast the raw shape in aluminium, then transform it (drill, turn, saw) to the PLA model.
2 identical units should be printed. Brim and support on build plate should be set when printing.
My printed sample is the Alpha version and is longer than needed. It's already modified on the STL file.
One could have a view on https://cults3d.com/en/3d-model/tool/universal-mandrel-v8-2-for-drill-or-lathe-16-40mm which also works on a drilling machine.
The author marked this model as their own original creation.