I don't know who is pushing CAD seats for free these days. I pay out the ears for mine.
for non-industrial stuff there is actually quite avariety of free software around.

If - like most 3d printers - you're just designing a single object, rather than a football stadium or car or aeroplane, then free cad is probably the way to go.

fusion 360 has a free option.
blender - while complicated - is also good and free.

Personally I can't draw so i use openscad. I wouldn't want to design a car with it - but have yet to find anything I can 3d print that I can't design.

tinkercad is popular, it's an autodesk product, but made simple.

Back to the lure.
Use trace wire for the inside of the lure, the hole will have rough edges and normal fishing line will fray over time.