Parametric Hex Knurled Cap

I found https://www.thingiverse.com/thing:4276492 but it doesn't work with customizer and is complex. I just need something simple. So put together this model.

STL attached and default values are for M4 screw.

Creates a simple cap with vertical ridges for knurling. No other libraries needed. Source includes some commentary on what I did to make it for those curious.

NOTE for Customizer: it doesn't show the knurling. The final model does have it.