I was prototyping an orrery. It involved cutting out a lot of ad-hoc gears and frame bits on my CNC out of a sheet of brass. It was relatively easy to generate the g-code for the individual parts using fusion360, but then it was a lot of faff to zero the machine such that it cut the part from a fresh part of the brass sheet without wasting too much metal in between the parts. It involved a lot of guesswork, and eyeballing. And even with that there was a lot of brass “wasted” between the parts especially since you could only move your part in x-y but not easily rotate it.
As a solution I wrote a python script which converted the g-code into svg, and a simple one page website where i could drag the svg around and rotate it on a visual representation of the sheet. Once i found a good safe spot for it to be cut the page told me the x,y, theta coordinates for it. And then with a separate python script i could transform the g-code using the coordinates and rotation. This way the svg renderer was doing the heavy lifting of visualising the cutting paths, and i only needed to concentrate on the relatively easy transforms.