How to make a structure spawn only once?

I don't believe this is possible. just make it really rare (like 1 structure per 1,000,000 chunks

Interesting idea, also thought about it, though decided it's unpractical in my situation.

But for playability case, I suggest making anything that can lead you to such structure. With generating only one per world, sometimes it can be impossible to find one.

Create a structure, for example using structures blocks in a test world then add the structure in the mod.

Then add a variable in the variable tab in the workspace with the name you want, with variable type set to string and variable scope set to global_world.

Then add a procedure and change it's event trigger to something like "player joins the world"

add " IF [get global [Your variable] ] = false then

place at 0 0 0 (you can change the coordinates) with rotation [You choose] mirror [You choose] structure [Your structure]

set global [Your variable] to true

This way everytime a player joins the game will attempt to spawn the structure at the coordinates, but it will only do so if the structure doesn't already exist (if your variable is on false)

wait--global_world will be reset every time the player goes to another dimension.use global_map instead.

What version are you using? If it is the mcreator snapshot I have the solution

I'm also wondering and I'm using the snapshot. Can you tell me, please?

When I try to do the procedure you said there is no way to put in the false anywhere.

when World is made spawn at  x y z structure