Injection of dense collagen to obtain 3D biomimetic scaffolds in terms of structure and mechanical properties is challenging for regenerative medicine since it would avoid open-surgery. It is well-known that highly concentrated collagen solutions can form liquid crystal mesophases with tissue-like geometries. Thus, it is possible to obtain 3D collagen gels in vitro with better mechanical properties, without widely used chemical crosslinkers that may lead to inflammatory responses. Nevertheless, the injection of highly concentrated collagen solutions is unlikely due to their high viscosity.How to combine biomimetism and injectability of dense collagen gels?To achieve this goal we concentrate acidic collagen solutions by spray-drying, forming dense collagen beads. A simple weighing of the beads determines the concentration of the gels. Mixed with an aqueous solvent, the beads are injected into a mold mimicking a tissue defect. The fibrillogenesis in vitro is induced within the collagen solutions that transform into stiff gels. Electron and polarized light microscopies show organizations resulting from collagen self-assembly at macroscopic length scale depending on the collagen concentration i.e. from 3wt% to 8wt%. Mechanical tests results reveal tissue-like properties strongly linked to collagen fibrils ultrastructure. This study opens perspectives in tissue repair in setting the framework of a library made of biomimetic (anisotropic, dense and stiff) and injectable collagen gels, enabling minimally invasive procedures.