x1 = 0;
x2 = Pi;
n = 9;
y0 = 1;

Point (1) = {0, y0, 0};
For i In {1:n}
  x = x1 + (x2 - x1) * i/n;
  Point (i+1) = {x, y0 + Sin (x), 0};  
EndFor

// above was typed, below was generated via GUI

Spline(1) = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
Extrude {{1, 0, 0}, {0, 0, 0}, Pi/2} {
  Line{1};
}
Extrude {{1, 0, 0}, {0, 0, 0}, Pi/2} {
  Line{2};
}
Extrude {{1, 0, 0}, {0, 0, 0}, Pi/2} {
  Line{6};
}
Extrude {{1, 0, 0}, {0, 0, 0}, Pi/2} {
  Line{10};
}
Line Loop(18) = {4, 8, 12, 16};
Plane Surface(19) = {18};
Line Loop(20) = {3, 7, 11, 15};
Plane Surface(21) = {20};
Physical Surface(22) = {19};
Physical Surface(23) = {21};
Physical Surface(24) = {5, 17, 9, 13};
