I don't have an usecase, I don't own a printer even. But this is actually a good piece of software - it seems non-trivial from algorithmic point of view, UX is also well polished. Kudos to authors.
Same — as someone building macOS utilities I have a soft spot for indie apps that tackle genuinely hard algorithmic problems and still manage to ship a clean UI. The gap between "technically interesting" and "actually usable by non-experts" is huge, and it looks like they've bridged it well here.
The usecase for Unfolder or Pepkura isn't 3D printing. They're targeted at paper crafting. You print the unfolded file onto paper, cut, fold, and glue to create a 3D object. Something like these samples <https://duckduckgo.com/?t=ffab&q=paper%20craft%20models&ia=i...>