In a recent video [Brick Sculpt] breaks down this fascinating topic. So, what is an LDU precisely? It’s the smallest incremental size used to define LEGO’s dimensions. For context, a standard ...

Box4Blox is a simple sifter that sorts your lego blocks by size. It works by grading the bricks. Of the four layers, three have holes in the bottom which only let through a certain size of brick.