i have decided to make an 18' bass cabinet to go under my 410 RBX by GK

i am using the Eminence OMEGAPro 18":

because it matches the 8 ohm 800Watt power rating i need

also the dimensions of the cabinet will be 23.5"(w) x 26.5"(h) x 18.5"(d) so that it is stackable with the 410 RBX

i need advice on how to brace it(so it can hold atleast 150lbs), have castors at the bottom, have two slotted ports at the top and bottom, also(hopefully) have handles, and i am going to have it be carpeted, and have interlocking corners that match with the 410RBX
i am going to use 11-ply poplar

any diagrams or help would be great because this is my first cabinet i will build