You will need:
Wood planks of you choosing
Fence
And any kind of slab
Bulid 4 up with the wood planks then bulid 7 over and 4 down again. Then take the fence and bulid 2 down 1 block away from the wood planks repeat on the other Side there should be a small space between the two fences than on the bottom of one fence bulid 3 over and done!