Hi there,
This is Bogdan from Romania.
I'm a mechanical engineer - specialized in the industrial robotic field, 3D designer and modeler (from time to time and some projects I could make the functional prototype too).
I'm doing product design, industrial design, reverse engineering, ideation, etc.
I have over 15 years experience working on various systems/devices across multiple industries, from concept to launch.
1 - i'm working in autodesk inventor 2017 and the native file format is ipt, but i could save/export as iges, step, etl, obj, x_t
2 - you ask for a hex head, but in the pics shows a squared head (most probably you want to fix the tool directly in the chuck instead of using the adapter...)
3 - there are some "tricky" things on the pics - looks like the spline is left and right.. and they intersect...
4 - would be useful a drawing with some explanations and dimensions...
btw - for higher accuracy try to 3d print the model on another printer (fdm printers sucks... - i have my own and i know)
Regards
Bogdan