Basically it defines a framed area of the map that should hold the majority of a ship's pixels. Then adds some sticky points within that frame to act as the initial valid positions for components to stick to. Then throw a few hundred randomized components (not fully random, generated from the ships 'palette' of components), usually small rectangles and angles at it. There's a very messy algorithm determining when they successfully get added. And a few post generation things where it fills in some gaps and trims things up.
I'm pretty happy with the result at this stage, but there were a lot of other things I wanted to do. My last day of the jam was spent building the minimalist ui and packaging it. Glad you like them.