I tried lots of variations to increase the finger comfort. Then I realised its best to use plain cyclinder with textured surface like dumbells.
Enable the “Fuzzy skin” option before slicing to create the grippy surface. Also I recommend using brim to increase the adhesion.

I used TPU-95 with 4 walls and %40 infill so it became pretty tough.

It's my first ever 3d design. You may want to change something, so the step file is included.

V2 Version
Lower cyclinder gap to prevent rolling.