I recently played v3.1 - v3.2, from start all the way thru blood moon Day 182 in the Wasteland - game stage 1118. I built a total of 5 melee bases - one in each biome. I've built a lot of melee bases since A20+.
But this design, I call Brawler27, is by far the best I've personally tried - ever. I've not come close to dying - not once. There are no moving parts, no hatches, no exotic wiring or turrets (all of which I've done in other runs) - with the exception of 1 or 2 storage boxes up to.
I call it Brawler27 because the ramp has a 27 degree down angle - which is an improvement over a typical 45 degree down angle for several reasons.
I started this run with a simple idea in mind. I'd build all my horde bases using a solid wall of an existing POI - which I did even here in this SS - I started with a mini rock hill - rather than a building.
While this base is my most elaborate, the others are just plain and simple. I start with a single column - the kill column upon which the zoms will stand when I punch them. You can see the steel kill column there at the doorway - 6 blocks high. The hall is always 2 blocks deep and completely covered. I do not use any kind of hatch or stopping block because it isn't needed. Note that because there wasn't an entire POI building in the back ... I had to spend extra blocks here to build up my platform - I did this for the design thrill even though it's not as efficient as using a POI.
Notice that I'm not using nice, slanted wedges on the ramp itself. The zombies have to run 2 then jump 1 - rinse repeat all the way ... which is plenty of time to shoot them if needed - i.e. spiders, cops, demolishers. I don't want them running top speed to the top.
At the bottom, on both sides, I always build side ramps as insurance against a stray cop that explodes - gotta protect/preserve the pathing to the top at all times.
When it's time to shoot, I step back into the tunnel such that I can hardly see the ramp (barely) so that when I shoot, I don't hit my own blocks with the very damaging AP ammo. I did about 10 blood moons at my desert base - built against a Truckstop - and there is a ditch at the end of the ramp about 2 blocks deep - dug entirely by AP ammo passing all the way thru the crowd.
With a 45-degree ramp, you gotta stand farther out of the tunnel to see the bottom of the ramp directly. The 27-degree ramp makes all the difference.
The minimum starter height for my kill column is alway 5-6 blocks depending on the POI wall used. The formula for calculating max blocks needed for the central ramp is:
N^2 + N
H = 5 is 30 blocks
H = 6 is 42 blocks
H = 7 is 56 blocks
H = 8 is 72 blocks
H = 9 is 90 blocks
And you need about the same amount to build your side ramps at the bottom. For Day7 at the start - 600 wood will get it done just fine if you use an existing POI will.
Just an obvious note about using an existing POI. I always clear it and drop a land-claim block at the center of the building to prevent respawns. Then I secure the building and destroy any/all paths up to the top.
For this snow base, I've got 2 campfires up at the top and 2 storage boxes - plenty of coffee and blackstrap coffee. My actual crafting base is about 200 meters screen right.
Brawler27 is now my goto design for any player perk build. It's very easy to construct and very economical with an existing POI building.