How do I add isocaps to the other voids/around a gyroid?

clc
clear
close all

Nx = 10; 
Ny = 10; 
Nz = 10; 

% Generate meshgrid for the entire structure
x = linspace(0, 2, Nx*10);
y = linspace(0, 2, Ny*10);
z = linspace(0, 2, Nz*10);
[X, Y, Z] = meshgrid(x, y, z);
ri=-0.35;
ra=-ri;
F=cos(2.*pi.*X).*sin(2.*pi.*Y)+cos(2.*pi.*Y).*sin(2.*pi.*Z)+cos(2.*pi.*Z).*sin(2.*pi.*X); 
F=-(F+ri).*(F+ra);
 [fs,v]=isosurface(x,y,z,F,0);
 [fc,v2,c] = isocaps(x,y,z,F,0);
 fn = [fs ; fc+length(v(:,1))];
 vn = [v ; v2];
  TO = triangulation(fn,vn(:,1),vn(:,2),vn(:,3));
     trisurf(TO,'FaceColor','g','FaceAlpha',1,'EdgeAlpha',1,'EdgeColor','none')
      view(3)
      light;
      lighting gouraud
      camlight
      title('Gyroid');
     stlwrite(TO,'Gyroid.stl');

I have added isocaps as above to close the wall between the 2 distinct volumes. I now want to add another isocap to the 4 sides of the gyroid so that it can be mesh'able for further pde numeric analysis. Please guide me.