This video explains how to construct the crystal structure of the 2:1 phyllosilicates (i.e., the mica and pyrophyllite-talc groups) using TotBlocks, a series of 3D-printed building blocks. The structure of the 2:1 phyllosilicates at the atomic scale, that is, their infinite sheets of T-O-T modules, influences their macroscopic mineral properties. In particular, the weak vertical bonds lead to platy habits and a perfect basal cleavage. The 2:1 phyllosilicates structure can be thought of as a protostructure for rock-forming minerals that are made of T and O modules.