Walt Tschinkel is a genius:
In this paper, I describe a method based on the burial of a nest constructed of ice. The hollow space that remains after the ice melts is a facsimile of the ant nest as designed by the experimenter.
Want to see, in the field, how a colony of ants reacts when introduced to an alien architecture designed by a different species? Or, perhaps you’d like to establish lab-altered colonies in a field experiment without wasting energy on nest construction. Or, maybe you’re just looking for a kinder, gentler way to release pet ants back to their original habitat. Either way, the field-melted ice nest is an elegant technique.
source: 2013. Tschinkel WR (2013) A method for using ice to construct subterranean ant nests (Hymenoptera: Formicidae) and other soil cavitiesMyrmecological News 18: 99-102.