inkscape is a genious vector drawing program

it is a bit complex though and takes time getting used to

hostnamectl; # tested on
  Operating System: Debian GNU/Linux 10 (buster)
            Kernel: Linux 4.19.0-18-amd64
      Architecture: x86-64

Inkscape 0.92.4 (5da689c313, 2019-01-14)

1. install the inkscape extension:
   • exit inkscape
   • as non-root default user:

   • cd ~/.config/inkscape/extensions/

   • wget https://raw.githubusercontent.com/hawley577/Inkscape-Rounded-Corners/master/README.md

   • wget https://raw.githubusercontent.com/hawley577/Inkscape-Rounded-Corners/master/RoundedCorners.py

   • wget https://raw.githubusercontent.com/hawley577/Inkscape-Rounded-Corners/master/RoundedCorners.inx

2. start inkscape again
3. create a polygon in Inkscape using the pencil tool (or any other tool)
4. select the object
5. Path -> Object to Path
6. click extensions->Modify Path->Rounded Corners
   • extension should show up here:
     • 
7. Fill out the options in the dialog that pop up
   • 
   • Choose the radius for rounding
   • Pick units (Inches, centimeters, etc.)
   • pick whether you want left corners, right corners, or both to be rounded
   • select “Live preview” to see how your selections affect the shape before applying
8. Click Apply.
9. 

 

creditz:

https://github.com/hawley577/Inkscape-Rounded-Corners

as seen here: https://superuser.com/questions/640954/inkscape-rounding-corners-of-shapes

inkscape logo as svg:

https://media.inkscape.org/static/images/inkscape-logo.svg