The project by [Jan Mrázek] is called KiKit and works on .kicad_pcb files to arrange them in a grid with your choice of mousebites or v-cuts for separating the boards after production.
A few days ago, KiCad 8 was released, and it’s a straight upgrade to any PCB designer’s quality of life. There’s a blog post as usual, and, this year, there’s also a FOSDEM talk from ...