Most of the racks require assembly.. Some of the reptile cages like the AP ones require some assembly and sealing I believe.

Wait for more answers from people who have these because if you're only looking for one good enclosure like a 2x2 or a 2x3 type PVC cage for one BP even some of them require some assembly.

My 2x4 boaphiles came fully assembled tho. Even the heat was already attached to the bottom.