Foot print of this box is 36"x36"x24". Single layer. This current product is offered in two dog configuration. 
Material is HDPE Marine grade plastic. 3/8" thick. Stainless fasteners. This configuration has gone under multiple changes and has been tested for last two years. Its holding up great and looking forward get these out there. 
 
Please call to place ordering and to take care of shipping needs. These will be shipped and needed to be screw'd together. Very simple.