Type
Through-hole
Through-hole uses a flat open top — set the top to Flat for a clean result.
Flats (D-shape)
Press fit (grip ribs)
Print matching stick too
The stick sits in the same STL next to the knob — arrange freely in your slicer (print the stick lying flat so the cross shape holds better). Dimensions = real Lego axle 4.8/1.8. Enable the grip ribs above for a tight fit in the knob.