Self-made image, converted from a version of the following self-authored PostScript vector source code:

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270 396 translate 30 setlinewidth/A{gsave 42 setlinewidth .9 setgray
stroke grestore stroke}def gsave 42 setlinewidth .9 setgray 1 setlinecap
-100 2 sqrt mul -100 moveto 0 -100 2 sqrt mul 5 sub rlineto stroke
5000 sqrt neg dup 105 sub moveto -100 2 sqrt mul 0 rlineto stroke
5000 sqrt dup 100 2 sqrt mul add exch moveto 100 100 rlineto stroke
1 setlinejoin
45000 sqrt 5000 sqrt 100 add moveto 100 0 rlineto 0 -100 rlineto stroke
grestore 0 0 100 0 360 arc closepath A -100 2 sqrt mul 0 100 45 315 arc
100 2 sqrt mul 0 100 135 225 arcn closepath A 42 setlinewidth .9 setgray
0 0 100 30 60 arc stroke 0 0 100 210 240 arc stroke
-16 -16 moveto 16 16 lineto stroke 30 setlinewidth 0 setgray
0 0 100 29 61 arc stroke 0 0 100 209 241 arc stroke
-17 -17 moveto 17 17 lineto stroke 1 setlinecap
-100 2 sqrt mul -100 moveto 0 -100 2 sqrt mul 5 sub rlineto stroke
5000 sqrt neg dup 105 sub moveto -100 2 sqrt mul 0 rlineto stroke
5000 sqrt dup 100 2 sqrt mul add exch moveto 100 100 rlineto stroke
1 setlinejoin
45000 sqrt 5000 sqrt 100 add moveto 100 0 rlineto 0 -100 rlineto stroke
showpage
%EOF