Suffocation

Holding Left Shift and right-clicking an existing block shoves the held block into that exact space, and a Multi-Block forms from the combined blocks. Extend Block adds a held block to an adjacent space, which makes it possible to build compressed structures outward. Each block inside a Multi-Block keeps its own interactions, entities and redstone capabilities, so the combination works as a functional stack rather than a purely visual trick.

Pistons cannot push or pull Multi-Blocks, and slime or honey blocks placed inside one can still drag adjacent blocks, which matters for redstone contraptions that take up too much room. Chests, furnaces, hoppers and modded machines can share a space, and the mod uses a proxy system so that an opened chest or furnace shows its own GUI. Both the server and every player need the mod installed, and it is published for Forge 1.20.1 only, under All rights reserved. The code is not open source.