Inputs are vectors giving the x, y and z range. e.g x=1:100;y=40:70;z=80:250;

Apologies for lack of description but this submission is for a specific request. It is an extract from a much larger program.

% - B.I SOLID POINT CLOUD CUBOID
function [P]=Cuboid(x,y,z)
% - Generates coordinates for a solid cuboid composed of points

a=length(x);b=length(y);c=length(z); % assigning for coding simplicity
% B.I.1. Finding all x coordinates
xp=zeros(1,a*b*c); % preallocating
for nx=1:a
if nx==1,xp(1:c*b)=(repmat(x(nx),1,c*b));
else xp(((nx-1)*c*b)+1:nx*c*b)=repmat(x(nx),1,c*b);end
end
% B.I.2. Finding all y coordinates
yp=zeros(1,b*c); % preallocating
for ny=1:b
if ny==1,yp(1:c)=repmat(y(ny),1,c);
else yp(((ny-1)*c)+1:ny*c)=repmat(y(ny),1,c);
end
end
yp=repmat(yp,1,a);
% B.I.3. Finding all z coordinates
zp=repmat(z,1,b*a);
% B.I.4. Coordinates of the cuboid generated.
P=[xp;yp;zp];
end % To Optimize