The development of science and technology provides the availability of sophisticated products but concurrently increases the use of flammable materials. Those must therefore be flame retarded to make them safer. In case of fire, people must be protected by materials confining fire and forming fire barriers. The design of smart fire barriers triggering at the right time and location, and responding accordingly to the type of fire exposure is consequently of prime importance. The European project FireBar-Concept is dedicated to the development of such smart barriers. This work, in the frame of this project, deals with the design of flame retarded multi-materials. Therefore, two concepts are studied. On one hand, Intumescent Polymer Metal Laminates (IPML). Indeed, intumescent paints are applied on materials to protect them against fire, but the development of novel chemistries has reached some limits. Moreover, the recent concept of “Polymer Metal Laminates,” consisting of alternating thin aluminum foils and thin epoxy resin layers has been proven efficient against fire, due to the delamination between layers during burning. Both concepts were considered to design “Intumescent Polymer Metal Laminates” (IPML), i.e., successive thin layers of aluminum foils and intumescent coatings (i.e. materials with a very different thermal expansion coefficient). The use of IPML revealed a clear improvement at the beginning of the test. Other characterizations were carried out on the different samples and suggested that the polymer metal laminates (PML) design delays the carbonization of the residue. This first concept highlighted that design is as important as the chemistry of the formulation to obtain an effective fire barrier. On the other hand, the second concept consists in the elaboration of new designs of multi-materials using 3D printing. The aim of this study is (i) to elaborate a flame retarded multi-material composed of materials with different chemistries containing different additives, and (ii) to change the design to evaluate if and how it impacts the fire protective properties. First of all, a comparison between thermocompression versus 3D printing process in terms of fire protection properties was realized. Then, a simple design as bilayers or three-layers was tested. Finally, a complex design will be presented in this talk.