i was bored

I can see there are diagonal axis, but I can't figure out yet how to start. I've
only got a few squares from the 612216 lines. I'll have to come back to this.

Clue - the bottom left corner is black.

I have to say it was pretty hard ,but fun :)

Flippin' heck - that was tough!

One unique solution. Thank you for the puzzle!

Another artistic guessing.