Two layers

-- 1 - obsidian
-- 2 - quartz

shrek1={
       {1,1,1,1,1,1},
       {2,0,0,0,0,1},
       {2,0,0,0,0,0},
       {2,0,0,0,0,1},
       {1,1,1,1,1,1,},
       }

shrek2={
       {2,3,3,3,3,1},
       {1,0,0,0,0,3},
       {1,0,0,0,0,0},
       {1,0,0,0,0,3},
       {2,3,3,3,3,1},
       }

shrek3={
       {1,0,0,0,0,1},
       {4,0,0,0,0,1},
       {1,3,3,3,3,1},
       {5,0,0,0,0,3},
       {1,0,0,0,0,3},
       {5,0,0,0,0,3},
       {1,3,3,3,3,1},
       {4,0,0,0,0,1},
       {1,0,0,0,0,1},
       }

function buildLine (colors)
    for i = 1,#colors do
        slot = colors[i]
        if slot~=0 then
          turtle.select(slot)
          turtle.placeDown()
        end
        turtle.forward()
    end
    turtle.turnRight()
    turtle.forward()
    turtle.turnLeft()
    for e = 1,#colors do
        turtle.back()
    end
end

function buildLayer(image)
    for i=1,#image do
         line=image[i]
         buildLine(line)
    end
  turtle.turnLeft()
 for i=1,#image do
    turtle.forward()
  end
  turtle.turnRight()
  turtle.up()
end


 buildLayer(shrek1)

 buildLayer(shrek2)

turtle.turnLeft()
for g=1,2 do
  turtle.forward()
end
turtle.turnRight()

buildLayer(shrek3)