Today I sawed the corners and turned the rectangle octagonal.
Unfortunately I forgot the jigsaw blade at home and the Dremel blade is too small, so I had to use a hand saw.
After sawing, I smoothed it all out using a file. The result is not perfect, but since it all done using only manual tools I am quite satisfied.
Thanks guys, it is the same workshop as previous pictures .
Looks like I will not change this place unless someone will kik me from there.
I am also using this spot to work on my camper car conversion so it is a busy workshop