very cool jo. i've been using something quite similar and it does work very well and takes up little space.
one word of advice though on putting two plastic tubs (aquariums would be fine because of their weight) vertically into the rack side by side--if the tubs overhang the shelves much at all on either end your rats will find a way to somehow make it fall off the rack. :o i put two tubs like that as a test one time and as i sitting on the floor cleaning the tubs below the boogers in one of the vertical tubs managed to make this happen, which resulted in their tub falling on my head, the top flying off, covering me in aspen, water, food and freaked out rats. fun! they must have all run to the edge and jumped up and down or something--i have no idea--but i quickly decided that that wasn't going to be a good idea.![]()