aero system needed. 36 plants in 4' x 4'.. 8" squared root space for each plant

so i had plans to get the general hydro aeroflo 36 for a while now but i just saw it in person and the growing chambers are smaller than i thought. there only 5" wide and 5" in height. i dont know why they designed it like that but i need bigger root space with the same amount of plants and by my math its 8" x 8" for every plant. is there any systems like this sold on the market? i desperately need to find one cause i dont even wanna try to build one myself.