Hey,
Does the Autoheight didn't exist anymore? Because in the ingame help i see that option, but when i try to use it it doesnt work.

it would be great to make Autoconfig Heights. Every time I want to insert a building, it's either high or below ground

You can specify how high the building is supposed to be with the height parameter, this disables the AutoHeight (enabled by default) besides this I don't really know how to implement this.
I normally just get it to paste correctly once on the spot I like and then from there use /pasteback to place the building back.

Thing is that facepunch changes the seeds often. Seed 1 is often different on a wipe by wipe basis so pasteback puts stuff in a mountain, in the air, or even under water.

So if you see that the terrain changed drastically just use /paste [filename] height 1 for starters. 
You can test it by trying to add a foundation on the lowest and highest sides.
If it isn't to your liking do /undo and try to increment the heigth to whatever works.

you can do /paste [filename] height .5, or any number.

Even negitive values but I find .7 to 1 usually gets it done.

Yeah in the future I might have a look at the AutoHeight, the only real thing there is the fact that if you decide to specify height the building suddenly completely changes location since it will disable AutoHeight.
So something like a modifier to the AutoHeight which can be specified just like the Height parameter would be nice I think.

For now I just want to get some work done on optimizing the plugin so it doesn't make the server freeze when working with larger buildings.

what is the best way to send the file to you?
as .rar it's small. Only 1.5mb, but extracted it's 50 mb.

Thing is, the base would never be allowed on any server. When I paste, and I need to undo, I just roll server back rather than undo.

So it's not realistic that you make that base smooth with copypaste, because pasting it drops my server from 800fps to 400fps permanently when its on the server. Rust in general can't really handle it.

Getting to this pretty late.
AutoHeight is enabled by default so you shouldn't have to specify the parameters for it to work. If you specify a height with it it will get disabled (something I'm planning to change in the future)

Hi Misstake, will this save an Arena that you build for PVP and then after a wipe, you can restore it?

I put a lot of effort to build a PVP arena and like to save it.