You can now Export your structure into .mcstructure file.

— Save mode allows the player to highlight a structure in the world and save it to a file.

— Used to Export a structure into a .mcstructure file, which can be used to load from the structures folder of a behavior pack. If the structure contains a custom block from a behavior pack, then the block is also saved on the structure block. 

Before entering in New Created World activate this

Experiments Features