LOL, I meant that you need more than a tin can or aluminum foil on your rocket ship in order to withstand the pressure of an absolute vacuum, and the nozzle we had been discussing would likewise have to be made of very interesting material to withstand a boundless, infinite vacuum.
There is no pressure in a vacuum. The only pressure a ship has to contain is it’s internal atmo. 14.7 psi is sea level pressure on earth.