In the first attempt, I didn't pick up that the piece resized itself when loaded onto the laser-cutter PC, so the gap sizes weren't what was originally set.
In this 2nd attempt, I used default settings of 'y' line length 19mm, 'y' gap size 3mm, 'x' separation 1.5mm. The rectangular outline was created as 100mm wide (x) by 75mm high (y), before selecting Extension > Render > Living Hinge, and accepting the 3 default settings above. That's all there is to it, before Path > Object To Path, & re-saving as DXF. After loading on the laser-cutter PC, I was careful to re-size to 100 x 75mm before cutting.
The back of the piece doesn't have any of the scorch marks, but isn't particularly interesting:
The front has some scorching, but (at this scale) it seems to give the whole surface a warm glow:
Bearing in mind this piece is only 100mm wide, I'm impressed that it can be bent into a semi circle - so maybe 200mm and larger could be formed into a tight cylinder (at least for 3mm MDF):