Abstract Intracranial aneurysm is a life-threatening pathology related to the arterial wall alteration. As yet there is no method capable of predicting rupture risk based on quantitative in vivo mechanical data. This work is part of a large-scale project aimed at providing clinicians with a non-invasive patient-specific decision support tool, based on the in vivo mechanical characterisation of the aneurysm wall. First, an original wall deformation device was developed on polymeric phantom arteries. These artery models were obtained by 3D printing and an injection moulding process, each one showing pros and cons of designs of a biofidelic phantom in terms of thickness and local stiffness. A numerical modelling of this experimental study was built as a support for designing phantoms as design process choices and determining the geometrical and mechanical parameters of arteries. A numerical Fluid–Structure Interaction model based on the finite element method was developed. Several wall thicknesses, mechanical properties and deformation device locations were considered. Regarding the 3D printed phantom artery, the numerical model demonstrated that a thin wall thickness should be emphasised instead of a low Young’s modulus to reach a significant and experimentally observable strain. Regarding the injection moulded phantom, the results pointed to a locally reduced aneurysm thickness with a Young’s modulus of 0.7 MPa for the strain analysis. The numerical study provided helpful information regarding the scientific challenges of the experimental study. This work is the keystone of further animal studies and associated patient-specific models.