I think "egg crate dividers" or 'egg crate construction' carries the idea across. Might not be the most apt or correct terminology but I have used it describing similar constructions and everyone seemed to pick up on what I meant.
WARNING & DISCLAIMER:
SELECT AND USE OUTDOORS AND SURVIVAL EQUIPMENT, SUPPLIES AND TECHNIQUES AT YOUR OWN RISK. Information posted
on this forum is not reviewed for accuracy and may not be reliable, use at your own risk. Please
review the full WARNING & DISCLAIMER about information on this
site.