The small fit that makes a brick hold
A LEGO connection is a carefully controlled squeeze, not a latch. The studs on one brick meet the hollow tubes beneath another, and the parts are made to fit tightly enough that their surfaces press against each other. That pressure creates friction: resistance to sliding, which keeps the bricks from separating under ordinary handling.
The plastic also gives slightly under pressure. That tiny flex helps the surfaces stay in contact, while the molded shapes guide the pieces into alignment. Connect several studs at once and their combined grip makes a larger assembly feel solid, even though no glue or moving fastener is involved.
Why the fit has to be just right
If the connection were looser, a model could come apart as it was picked up. If it were much tighter, building and rebuilding would become tiring—and parts could be stressed when pulled apart. The design therefore depends on consistent molding: studs, tubes, and surrounding surfaces must be shaped closely enough to produce a dependable grip across many pieces.
That balance is why a firm connection can still be reversed. Pulling straight apart takes more force than sliding the surfaces together during assembly, especially when many connections are engaged at once. The same simple friction that lets a brick stay put is what makes a tightly built model stubborn to dismantle.
