Instructables

Step 4: The Walls and Doors

Level 6 - Wall 2.png
The walls were originally clear, in fact most of the case was until I discovered how hard it was to find clear pieces anymore. 
It looked really cool in LDD.

Level 5: Wall
7 - 1x2 Technic Brick      #32000
(The Technic Brick #3700 has 1 hole instead of  2 if you like)
1 - 1x1 Technic Brick     #6541
1 - 1x2 Brick                    #3004   Clear
1 - 1x1 Brick                    #3005   Clear
1 – Megaphone             #4349

Level 6: Wall 2
1 - 1x10 Technic Brick   #2730
1 - 1x8 Technic Brick     #3702
2 - 1x2 Technic Brick     #32000
2 - 1x1 Technic Brick     #6541
1 - 1x2 Brick                    #3004   Clear
1 - 1x1 Brick                    #3005   Clear
1 – 1x1 Round Plate     #6141
2 – 1x3x2 Left Doors     #3189    Blue
1 – 1x3x2 Right Door    #3188    Blue
2 – 1x3 Right Doors      #3821    1 Black, 1 Blue