Tissue Engineering (TE) reconstructs damaged tissues/organs exploiting biocompatible and biodegradable scaffolds, taking often advantage of natural materials' bioactive/biomimetic cues together with advanced 3D processing techniques. In this scenario, collagen-derived materials (e.g. gelatin) have played a pivotal role. This paper will review past and recent outcomes of my research in the field, focusing on how collagen-based materials have been transferred from TE to the realization of 3D tissue/organ models supporting disease monitoring and drug design in an increasingly sustainable and ethical approach. Pioneering experiments have shown the potential of enzymatic/genipin crosslinking to realize new biomaterials. Engineered fillers of porous hollow tubes have also been designed to guide peripheral nerve regeneration. A procedure for preparing bone-derived biomimetic soluble collagen was also developed “in-house”. More recently, collagen coatings with custom polyurethanes supported the modelling of healthy and osteoporotic bone. Collagen is, moreover, a key component to design 3D skin equivalents for assessing biological safety. Gelatin is also a key ingredient as bioink for 3D-bioprinting. For instance, gelatin/nano-hydroxyapatite bioinks have permitted the realization of bone models. Cellularized gelatin bioinks are also used to colonize polyurethane scaffolds mimicking the cardiac tissue. Electrospinning of gelatin and collagen membranes has been implemented, successfully, in the design of lung and pancreatic tissue replicas in disease modelling.