>>105599667per anon, /mjg/ has a decent amount of colonies but not that much. /jong/ is more then welcome to finish all the squares left. In fact this collage has been going on so long (I picked it up after the last anon left it unfinished) that some anons have probably done more then 1. But in general just pick a single square and go to town.
Here is an example of a previous collage.