data file for a cubic with fixed walls(4 walls)

hello dear users
i’m simulating a cubic that containes water-cu in lammps
i want to test sth.does anybody have a data file (in VMD or Moltemplate or Packmol) for a cubic (atoms or molecules aren’t important) which walls(it should have 4 fixed walls,microchannels have 2 fixed walls) are fixed and should be 4 walls.walls should be a metal like Si,Cu,… and in the middle any kinds of atoms can be placed…
I’ll thankyou verymuch and it’s necessary.
sincersely

hello dear
i’m working on a cubic.
i want to test sth.does anybody have a data file (in VMD or Moltemplate or Packmol) for a cubic (atoms or molecules aren’t important) which walls(it should have 4 fixed walls,microchannels have 2 fixed walls) are fixed and should be 4 walls.walls should be a metal like Si,Cu,… and in the middle any kinds of atoms can be placed…
I’ll thankyou verymuch and it’s necessary.
sincersely