WWII Luftwaffe Secret Base (late war/what-if?)

The idea behind this diorama was to build a hidden/subterranean base as a store for some of the experimental and prototype fighters of the late war - some of the “what if?” designs which never made it to production.

After having gained the experience of working on the WW2 French countryside ambush and WW2 German Airfield display, the idea of a larger, multi-level diorama hosting several of the advanced jets and rocket the German airforce was working on really appealed to me.

• Two level - upper 'ground' level and a lower maintenance/storage area.
• The upper level will be both 'open', with a runway/taxi-way section, and the 'hidden' entrance to the base in a hill or cliff face. Space for at least one model on the taxi way, and one more in or entering/exiting the base entrance.
• The upper level should be removable so that the upper and lower levels can be assembled seperately
• The upper level should have a removeable cover over the entrance, so that models can be placed and then the hill/cliff/earth cover added
• The lower level will have space for 3 or so fighters
• The lower level will have a suspended walkway leading to a control booth overlooking the maintenance bay
• The lower level will have a narrow gauge rail link, to transport in parts/fuel/ammo
• The lower level will have a crane to offload cargo from the rail cars
• Some working industrial lights (probably LEDs) hanging from the ceiling of the lower level and as wall lights in the entrance of the upper level - to work off the existing LED strip illuminating the cabinet

A very early sketch of the multi-level layout:

This excellent diorama from uschivdr.com also gives an indication of what the lower level should be like:

• 6mm Plywood - base, walls and 'roof'
• 20x10mm Pine strip wood - bracing for walls
• 10mm XPS foam - floors and walls
• 30mm XPS foam - roof of upper section/cliff/hill
• Polyfilla/Spackle - 'concrete' floor
• Laser cut suspended walkway
• Laser cut stairs
• Narrow gauge rails
• Ballast for rails
• Pine tree armatures
• Assorted static grass
• Normal sized plastic doors
• Large sized garage/metal doors
• Screws and woodglue
• Superglue