This is way too much fun.
Play with gcode in realtime:
https://nraynaud.github.io/webgcode/
G28
G92
G0 X10 Y10
G1 X20 Y10
G1 X20 Y20
G1 X10 Y20
G1 X10 Y10
G0 X10.1 Y10.1
G1 X19.9 Y10.1
G1 X19.9 Y19.9
G1 X10.1 Y19.9
G1 X10.1 Y10.2
G0 X10.2 Y10.2
G1 X19.8 Y10.2
G1 X19.8 Y19.8
G1 X10.2 Y19.8
G1 X10.2 Y10.2
G0 X10.3 Y10.3
G1 X19.7 Y10.3
G1 X19.7 Y19.7
G1 X10.3 Y19.7
G1 X10.3 Y10.3
