Hello
There need not be inverted commas over the geometry type in the line where "femodel" is defined. I have increased the "Hmax" value to decrease the run time of the code. The following code might help you:
rect1=[3
4
-530
530
530
-530
0
0
-530
-530];
C1=[1
0
0
228.6];
C2=[1
0
0
520.5];
C1 = [C1;zeros(length(rect1) - length(C1),1)];
C2 = [C2;zeros(length(rect1) - length(C2),1)];
gd = [C1,C2,rect1];
ns = (char('C1','C2','rect1'));
ns = ns';
sf='(C2)-(C1+rect1)';
dl = decsg(gd,sf,ns);
model = createpde("thermal","transient");
ge = geometryFromEdges(model,dl);
% 2D -> 3D extrusion
gd1 = extrude(ge,96);
figure
pdegplot(gd1,"FaceLabels","on")
model = femodel(Geometry=gd1);
model = generateMesh(model,Hmax=50,Hmin=1);
pdemesh(model)
