You can do irregular shapes the same way. I’ve made many odd-shaped double-sided pieces, you just add the extra cut to the first pass.
Here’s an example that illustrates what I mean:
Here’s another. The X in the middle is where the bitmaps for each side are engraved. The ‘flame’ is only on one side but cut on both so when I flip it, it’s perfectly aligned. (I work mostly in outline mode…)
