something more organic

1 draw a close curve ... apply Rebuild
2 extrude a little bit... delete the cap face ... select the border
3 apply a script named Blendcap

the max value seems to be 2.5 but you can exceed the number ( here i wrote 12 ) to obtain a rounder shape

if the border of the blend is splitted ( red line ) use the Blend command

blend is better in some case ( the cut line to split the border can be placed where you want to generate various shapes )

blend surface need to be closed by Planar command ... select the 2 faces join ... it's solid and can be " booleanized " ;)

la booléanisation du schmilblick ;)