My Kicad panelizer is now available as a very nice website where you can just copy-paste the kicad board you want to panelize, set the options, and get the panel back
https://panelizer.dev.cthu.lu/

and like.. it's *really* easy to use, surprised myself with that because normally adding mousebites and precisely connecting edgecut segments is a paaain

example of a panel that was done like this (but by hand, which sucks)