During the development of the body surface, organs of different 3D shapes, such as hair follicles and mammary glands, form from 2D epithelial sheets through cell-ECM interactions. However, it remains unclear how the ECM is involved in the formation of these various shapes. Our recent 4D imaging of developing mouse hair follicles has revealed “telescopic multicellular dynamics”, which may represent fundamental multicellular dynamics underlying the morphogenesis of body surface organs. In this study, we aim to elucidate the principles of cell-basement membrane interactions that underlie the telescopic dynamics. Our approach includes: 1) visualising and measuring basement membrane and multicellular dynamics, 2) developing basement membrane gels capable of separating functional modalities of the basement membrane, and functional analysis using these gels, and 3) simulating multicellular and basement membrane dynamics with mathematical models.