Here is my submission.
Entrance/Kill Zone
Interior of base
Outside view of base
Aftermath of 500 GS 7 day horde battle
My goals:
Make a "Normal" ish base (no cheesing) - no offense to cheesing, just wanted to see if a fairly normal base was viable.
Make it mind numbingly easy to defend (though I think most have this goal?)
Actually look like a base (alongside goal #1)
Have some fall back "Panic" room or two
I think I've accomplished it. I used a few more than 500 (I wanna say like 520?) blocks but I basically met the criteria. All it is is a single file death trap (10 barbed wire) for the zombies, wood shoot through grates (though probably won't really be used much since you can't really get in there with the traps), and not one but two panic room fall backs. One thing to do might be replace some of the walls in the panic rooms with gratings to shoot through also. Put most of your stuff up top on the third room for maximum security. I was getting every zombie in the game just about including Irradiated cops, and yet nothing got through, except once or twice a spider almost got me because they are sneaky and really low to the ground. I was actually surprised this design worked as well as it did. I have no doubt it would work even more amazingly at lower game stages although you wouldn't have an AK47 (well, you might) that early.
Note that the whole structure is Double walled. I found out through testing that double walling prevents zombies from being interested in attacking your walls.
Tested it on a ~500 game stage horde, on default difficulty, with very little damage to the base, with nothing but an AK with infinite ammo (Quality 1, at that).
NOTE: My game is lightly modded though, with some more higher level perks that's why I have 400 HP and 400 stamina, and used 200% block HP so the blocks did have more HP. 90% of the damage that was incurred was my own friendly fire spray damage from my AK to the ceiling blocks (lol oops).
Really the only main drawback of this design is that you basically need good ranged power, which may be challenging by day 7 unless you got lucky with some guns. Melee won't really work on this. Though one thing you could do is replace the barbed wire with spikes, if you need the extra damage assistance, and maybe throw up some spikes immediately outside as well. Also the way its set up you can't readily repair the wires farther away, which is also one unfortunate aspect to the design. However even on GS500, 2 or 3 wires remained at the end. Without a single repair.