The jigsaw block has been a recent block added in the 1.14 update. It is a very mysterious block used for technical purposes to generate structures. In the recent 1.16 snapshots, the block received some updates along with a new texture. In this post, I will explain each setting and how to use it. Also, the jigsaw block is used to generate structures saved in files. This means it's possible to create your own structures and save them with structure blocks. With the jigsaw blocks, you can then generate your own random structures!
SECTION 1 - STRUCTURE BLOCKS
Structure blocks are a feature that allows you to save structures and load them. You can load naturally generated structures too. For specific info on structure blocks, recommend going to the Minecraft wiki.
SECTION 2 - JIGSAW SETTINGS
To obtain a jigsaw block you will have to use commands as it is not in the creative inventory. The command (/give @p jigsaw) can be used to give yourself one. You can open the jigsaw block to enter some parameters.
This setting will tell the block which folder of structures to choose from(bastion/bridges/[blah]).
The name of the jigsaw block will only connect to other jigsaw blocks with the same name(for aligning structures)
This setting is used for the name of the structure to generate.
This is the block that the jigsaw block turns into once the entire structure has been generated.
This one I don't really know about...
GENERATE & LEVELS
The generate button will generate the next structure piece after the jigsaw block. It will continue generating the next structure's jigsaw block for x amount of layers.
If you use structure blocks to create the jigsaw file would it be possible to stack other structure blocks within it? So on the off chance it did generate and you discovered it you could load the structure blocks contained within the jigsaw generation to create bigger structures. Providing of course that you add the extra structure files to behaviour pack for that world. If this did work the possibilities are literally endless.
Im currently experimenting with a road/rail construction pack including tunnels and bridges on bedrock. Idea is you can you load up the behaviour pack in any world and build a network system for your world by placing just 1 structure block. The rest of the building options are presented to you in way of more structure blocks each time you place a new segment.
The thought of implicating structure blocks in world generation is very exciting. The chance to generate stacked structure blocks is mind blowing.