I'm happy to talk about modeling techniques and spend my spare time for it :)
This is MOI:a modeler first of all,not a script or math formulas container ;)
Jar tapered 6°
Rail revolve:yellow curves, profile and 8sides as rail
Draw a polyline (yellow) always extended to avoid problems when boolean difference
Fillet the polyline to 30 mm
Extrude in both ways,once again extended as said above
Rail revolve:this will be the Jar
Turn on previous surface
Polar array:8 copies
Bool difference:subtract 8 copies and deleting
Select solid and hit fillet=5mm
Pushing fillet to 40mm
model attached,open the browser to get construction lines
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